Ohms Law MCQ Quiz - Objective Question with Answer for Ohms Law - Download Free PDF

The correct answer is Resistance is constant for a given metallic wire at any temperature.

Key Points

• Resistance of a metallic wire depends on its temperature. As the temperature increases, the resistance of a metallic conductor also increases due to increased collisions of electrons.
• The statement "Resistance is constant for a given metallic wire at any temperature" is incorrect because resistance varies with temperature.
• For a given metallic wire, resistance remains constant only at a specific temperature, not at all temperatures.
• Ohm's law, which relates voltage, current, and resistance, assumes constant resistance only under stable temperature conditions.
• Materials like semiconductors and insulators exhibit a more complex relationship between resistance and temperature compared to metallic wires.

Additional Information

• Resistance (R):
  • It is a measure of the opposition to the flow of electric current in a conductor.
  • The SI unit of resistance is the ohm (Ω).
  • Resistance depends on material properties, length, cross-sectional area, and temperature of the conductor.
• Temperature Coefficient of Resistance:
  • It indicates how the resistance of a material changes with temperature.
  • Metals typically have a positive temperature coefficient, meaning their resistance increases with rising temperature.
• Rheostat:
  • A rheostat is a variable resistor used to control current by adjusting the resistance in a circuit.
  • It is commonly used for applications like dimming lights or controlling motor speed.
• Ohm’s Law:
  • It states that the current (I) through a conductor is directly proportional to the voltage (V) across it, provided the temperature remains constant.
  • The formula is: V = IR, where R is the resistance.
• Superconductors:
  • These are materials that exhibit zero resistance below a critical temperature.
  • Superconductors are used in technologies like MRI machines and particle accelerators.

The Correct answer is Voltage and Current.

Key Points

• Ohm's Law is one of the fundamental principles in electricity and electronics.
• It establishes a direct relationship between voltage (V), current (I), and resistance (R) in an electrical circuit.
• The law is mathematically expressed as: V = I × R, where:
  • V is the voltage in volts.
  • I is the current in amperes.
  • R is the resistance in ohms.
• Ohm's Law implies that if the resistance in a circuit is constant, the voltage and current are directly proportional to each other.
• This relationship helps in determining unknown quantities when any two parameters (voltage, current, or resistance) are known.
• It is widely used in the design and analysis of electrical circuits and is a fundamental concept in physics and engineering.
• Ohm's Law is applicable to linear circuits, where the resistance remains constant regardless of the voltage or current.

 Additional Information

• Current and Power
  • Power (P) in an electrical circuit is related to both current (I) and voltage (V) through the formula P = V × I.
  • While power is an important concept, it is not directly related to Ohm's Law, which focuses on the relationship between voltage, current, and resistance.
• Power and Resistance
  • Power can also be expressed in terms of resistance using the formula: P = I² × R.
  • Although resistance is a factor in power calculations, this is not the primary relationship outlined by Ohm's Law.
• Voltage and Power
  • Voltage and power are related by the formula P = V² / R when resistance is known.
  • However, this relationship involves power and does not directly represent the fundamental principle of Ohm's Law.

The correct answer is Option 2: V α I.

Key Points

• Ohm's Law states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points, provided the temperature and other physical conditions remain constant.
• The mathematical representation of Ohm's Law is: V α I, which can also be written as V = IR, where R is the resistance.
• This principle is fundamental in electrical circuits and helps in calculating voltage, current, or resistance in a circuit.
• The unit of resistance (R) is the ohm (Ω), named after the German physicist Georg Simon Ohm, who first formulated the law.
• Ohm's Law is not applicable to non-linear components like diodes or transistors, where the relationship between voltage and current is not linear.

Additional Information

• Voltage (V):
  • Voltage is the electrical potential difference between two points in a circuit.
  • It is measured in volts (V) and is the driving force for current flow in a conductor.
• Current (I):
  • Current is the rate at which electric charge flows through a conductor.
  • It is measured in amperes (A) and flows from higher to lower potential in the circuit.
• Resistance (R):
  • Resistance is the property of a material that opposes the flow of electric current.
  • It depends on the material, length, cross-sectional area, and temperature of the conductor.
• Limitations of Ohm's Law:
  • Ohm's Law is valid only for linear, ohmic materials where the current and voltage have a proportional relationship.
  • It does not apply to materials like semiconductors or devices like LEDs, diodes, and transistors.
• Applications of Ohm's Law:
  • Used in designing electrical circuits and determining required resistor values.
  • Helps in analyzing and troubleshooting electrical and electronic systems.

The correct answer is I = V/R.

Key Points

• Ohm's law states that the current (I) through a conductor between two points is directly proportional to the voltage (V) across the two points.
• The formula representing Ohm's law is I = V/R, where I is the current, V is the voltage, and R is the resistance.
• This relationship implies that if the voltage is increased, the current will increase, provided the resistance remains constant.
• Conversely, if the resistance increases, the current will decrease for a given voltage.
• Ohm's law is fundamental in the field of electrical engineering and electronics, providing a basic relationship between voltage, current, and resistance.

Additional Information

• Resistance (R): It is a measure of the opposition to the flow of current in a conductor. It is measured in ohms (Ω).
• Voltage (V): Also known as electric potential difference, it is the force that pushes electric charge to flow in a circuit. It is measured in volts (V).
• Current (I): It is the rate of flow of electric charge in a circuit, measured in amperes (A).
• Conductors and Insulators: Conductors allow electric current to flow easily due to low resistance (e.g., metals), while insulators resist the flow of current due to high resistance (e.g., rubber).
• Applications of Ohm's Law: It is used in designing electrical circuits, troubleshooting electrical problems, and understanding the behavior of electrical components.

The correct answer is 20 V.

Key Points

• Given that the heat produced in the resistor per second is 40 J, this corresponds to the power dissipation in the resistor.
• The power dissipated in a resistor (P) is given by P=V2R" id="MathJax-Element-35-Frame" role="presentation" style="position: relative;" tabindex="0">P=V2RP=V2R $P = \frac{V^2}{R}$ , where V is the potential difference and R is the resistance.
• Rearranging the formula to solve for V, we get V=P⋅R" id="MathJax-Element-36-Frame" role="presentation" style="position: relative;" tabindex="0">V=P⋅R−−−−√V=P⋅R $V = \sqrt{P \cdot R}$ .
• Substituting the given values, P=40 W" id="MathJax-Element-37-Frame" role="presentation" style="position: relative;" tabindex="0">P=40 WP=40 W $P = 40 \text{ W}$ and R=10Ω" id="MathJax-Element-38-Frame" role="presentation" style="position: relative;" tabindex="0">R=10ΩR=10Ω $R = 10 \Omega$ , into the formula, we get V=40×10=400=20 V" id="MathJax-Element-39-Frame" role="presentation" style="position: relative;" tabindex="0">V=40×10−−−−−−√=400−−−√=20 VV=40×10=400=20 V $V = \sqrt{40 \times 10} = \sqrt{400} = 20 \text{ V}$ .

Additional Information

• Ohm's Law
  • It states that the current through a conductor between two points is directly proportional to the voltage across the two points.
  • The mathematical formula is V=I×R" id="MathJax-Element-40-Frame" role="presentation" style="position: relative;" tabindex="0">V=I×RV=I×R $V = I \times R$ , where V is the voltage, I is the current, and R is the resistance.
• Joule's Law of Heating
  • It states that the heat produced in a resistor is proportional to the square of the current, the resistance, and the time for which the current flows.
  • The formula is H=I2×R×t" id="MathJax-Element-41-Frame" role="presentation" style="position: relative;" tabindex="0">H=I2×R×tH=I2×R×t $H = I^2 \times R \times t$ .
• Power in Electrical Circuits
  • Power (P) in an electrical circuit is given by P=V×I" id="MathJax-Element-42-Frame" role="presentation" style="position: relative;" tabindex="0">P=V×IP=V×I $P = V \times I$ , where V is the voltage and I is the current.
  • It can also be expressed using resistance as P=V2R" id="MathJax-Element-43-Frame" role="presentation" style="position: relative;" tabindex="0">P=V2RP=V2R $P = \frac{V^2}{R}$ or P=I2×R" id="MathJax-Element-44-Frame" role="presentation" style="position: relative;" tabindex="0">P=I2×RP=I2×R $P = I^2 \times R$ .
• Resistance
  • Resistance (R) is a measure of the opposition to current flow in an electrical circuit.
  • The unit of resistance is Ohm (Ω).
  • Resistors are used to control the current in an electrical circuit.

CONCEPT:

• Ohm’s law: At constant temperature, the potential difference across a current-carrying wire is directly proportional to the current flowing through it.

          i.e. V = IR

Where V = potential difference, R = resistance and I = current.

CALCULATION:

Given V = 18 V and R = 3 Ω,

• According to ohm's law:

⇒ ​V = IR

⇒ I = V/R

⇒ I = 18/3 = 6 A

Given:

• Two resistors, A and B are connected in series to a voltage source of 5V.
• Resistance of resistor A, R= 5 ohm​
• Resistance of resistor B, R'= 10 ohm

Formula Used:

Power in Watt (W), \(P=\frac{V^{2}}{R}\), where V is the voltage in Volt (V) and R is the Resistance in ohm.

Solution:

When two resistors, A and B, with resistances of 5 ohms and 10 ohms respectively, are connected in series, the total resistance of the circuit is the sum of the individual resistances:

R_total = R_A + R_B = 5 ohm + 10 ohm = 15 ohm

The total current I flowing through the circuit when connected to a 5 V source is given by Ohm's Law:

I = V/R_total = 5 V/15 ohm = 1/3 A

Now, we can calculate the power P dissipated in each resistor using the formula:

P = I²R

For resistor A (5 ohms):

P_A= I_A²R_A = (1/3)² * 5 = 5/9 W

For resistor B (10 ohms):

P_B= I_B²R_B = (1/3)² * 10 = 10/9 W

The ratio of power developed in resistor A to that developed in resistor B is:

Ratio = P_A/P_B = 5/10 = 1/2

Therefore, the ratio of the power developed in resistor A to that in resistor B is 1:2.​​

Given:

Heat Produced =200 J.

Registance=2 ohm.

Formula used:

Amount of heat produced \(H=\frac{V^2t}{R}\)

[Where V is the amount of Voltage produced; t is the time required ;R is the resistance]

Calculation:

\(200=\frac{\mathrm{V}^2 \times 1}{2}\\ \Rightarrow \mathrm{V}^2=400 \\\Rightarrow \mathrm{V}=20 \mathrm{v}\)    

Hence the correct answer is 20 volt.

The correct answer is 'Becomes nine times'. 

Key Points

• Hence the heating effect produced by an electric current, I through a conductor of resistance, R for a time, t is given by H = I²Rt.
• This equation is called Joule’s equation of electrical heating.
• Heat produced in the resistor H = I²RT

H = I2RT

• Heat produced after current is tripled.
• So Given I_new = 3I

H_new = I_new2RT

H_new = (3I)2RT

H_new = 9 I2RT

H_new = 9 H

So, heat produced in the resistor becomes 9 times if the current in the resistor is tripled. 

The correct answer is I = V/R.

Key Points

• Ohm's law states that the current (I) through a conductor between two points is directly proportional to the voltage (V) across the two points.
• The formula representing Ohm's law is I = V/R, where I is the current, V is the voltage, and R is the resistance.
• This relationship implies that if the voltage is increased, the current will increase, provided the resistance remains constant.
• Conversely, if the resistance increases, the current will decrease for a given voltage.
• Ohm's law is fundamental in the field of electrical engineering and electronics, providing a basic relationship between voltage, current, and resistance.

Additional Information

• Resistance (R): It is a measure of the opposition to the flow of current in a conductor. It is measured in ohms (Ω).
• Voltage (V): Also known as electric potential difference, it is the force that pushes electric charge to flow in a circuit. It is measured in volts (V).
• Current (I): It is the rate of flow of electric charge in a circuit, measured in amperes (A).
• Conductors and Insulators: Conductors allow electric current to flow easily due to low resistance (e.g., metals), while insulators resist the flow of current due to high resistance (e.g., rubber).
• Applications of Ohm's Law: It is used in designing electrical circuits, troubleshooting electrical problems, and understanding the behavior of electrical components.

The correct answer is 20 V.

Key Points

• Given that the heat produced in the resistor per second is 40 J, this corresponds to the power dissipation in the resistor.
• The power dissipated in a resistor (P) is given by P=V2R" id="MathJax-Element-35-Frame" role="presentation" style="position: relative;" tabindex="0">P=V2RP=V2R $P = \frac{V^2}{R}$ , where V is the potential difference and R is the resistance.
• Rearranging the formula to solve for V, we get V=P⋅R" id="MathJax-Element-36-Frame" role="presentation" style="position: relative;" tabindex="0">V=P⋅R−−−−√V=P⋅R $V = \sqrt{P \cdot R}$ .
• Substituting the given values, P=40 W" id="MathJax-Element-37-Frame" role="presentation" style="position: relative;" tabindex="0">P=40 WP=40 W $P = 40 \text{ W}$ and R=10Ω" id="MathJax-Element-38-Frame" role="presentation" style="position: relative;" tabindex="0">R=10ΩR=10Ω $R = 10 \Omega$ , into the formula, we get V=40×10=400=20 V" id="MathJax-Element-39-Frame" role="presentation" style="position: relative;" tabindex="0">V=40×10−−−−−−√=400−−−√=20 VV=40×10=400=20 V $V = \sqrt{40 \times 10} = \sqrt{400} = 20 \text{ V}$ .

Additional Information

• Ohm's Law
  • It states that the current through a conductor between two points is directly proportional to the voltage across the two points.
  • The mathematical formula is V=I×R" id="MathJax-Element-40-Frame" role="presentation" style="position: relative;" tabindex="0">V=I×RV=I×R $V = I \times R$ , where V is the voltage, I is the current, and R is the resistance.
• Joule's Law of Heating
  • It states that the heat produced in a resistor is proportional to the square of the current, the resistance, and the time for which the current flows.
  • The formula is H=I2×R×t" id="MathJax-Element-41-Frame" role="presentation" style="position: relative;" tabindex="0">H=I2×R×tH=I2×R×t $H = I^2 \times R \times t$ .
• Power in Electrical Circuits
  • Power (P) in an electrical circuit is given by P=V×I" id="MathJax-Element-42-Frame" role="presentation" style="position: relative;" tabindex="0">P=V×IP=V×I $P = V \times I$ , where V is the voltage and I is the current.
  • It can also be expressed using resistance as P=V2R" id="MathJax-Element-43-Frame" role="presentation" style="position: relative;" tabindex="0">P=V2RP=V2R $P = \frac{V^2}{R}$ or P=I2×R" id="MathJax-Element-44-Frame" role="presentation" style="position: relative;" tabindex="0">P=I2×RP=I2×R $P = I^2 \times R$ .
• Resistance
  • Resistance (R) is a measure of the opposition to current flow in an electrical circuit.
  • The unit of resistance is Ohm (Ω).
  • Resistors are used to control the current in an electrical circuit.

The Correct answer is Voltage and Current.

Key Points

• Ohm's Law is one of the fundamental principles in electricity and electronics.
• It establishes a direct relationship between voltage (V), current (I), and resistance (R) in an electrical circuit.
• The law is mathematically expressed as: V = I × R, where:
  • V is the voltage in volts.
  • I is the current in amperes.
  • R is the resistance in ohms.
• Ohm's Law implies that if the resistance in a circuit is constant, the voltage and current are directly proportional to each other.
• This relationship helps in determining unknown quantities when any two parameters (voltage, current, or resistance) are known.
• It is widely used in the design and analysis of electrical circuits and is a fundamental concept in physics and engineering.
• Ohm's Law is applicable to linear circuits, where the resistance remains constant regardless of the voltage or current.

 Additional Information

• Current and Power
  • Power (P) in an electrical circuit is related to both current (I) and voltage (V) through the formula P = V × I.
  • While power is an important concept, it is not directly related to Ohm's Law, which focuses on the relationship between voltage, current, and resistance.
• Power and Resistance
  • Power can also be expressed in terms of resistance using the formula: P = I² × R.
  • Although resistance is a factor in power calculations, this is not the primary relationship outlined by Ohm's Law.
• Voltage and Power
  • Voltage and power are related by the formula P = V² / R when resistance is known.
  • However, this relationship involves power and does not directly represent the fundamental principle of Ohm's Law.

The correct answer is Resistance is constant for a given metallic wire at any temperature.

Key Points

• Resistance of a metallic wire depends on its temperature. As the temperature increases, the resistance of a metallic conductor also increases due to increased collisions of electrons.
• The statement "Resistance is constant for a given metallic wire at any temperature" is incorrect because resistance varies with temperature.
• For a given metallic wire, resistance remains constant only at a specific temperature, not at all temperatures.
• Ohm's law, which relates voltage, current, and resistance, assumes constant resistance only under stable temperature conditions.
• Materials like semiconductors and insulators exhibit a more complex relationship between resistance and temperature compared to metallic wires.

Additional Information

• Resistance (R):
  • It is a measure of the opposition to the flow of electric current in a conductor.
  • The SI unit of resistance is the ohm (Ω).
  • Resistance depends on material properties, length, cross-sectional area, and temperature of the conductor.
• Temperature Coefficient of Resistance:
  • It indicates how the resistance of a material changes with temperature.
  • Metals typically have a positive temperature coefficient, meaning their resistance increases with rising temperature.
• Rheostat:
  • A rheostat is a variable resistor used to control current by adjusting the resistance in a circuit.
  • It is commonly used for applications like dimming lights or controlling motor speed.
• Ohm’s Law:
  • It states that the current (I) through a conductor is directly proportional to the voltage (V) across it, provided the temperature remains constant.
  • The formula is: V = IR, where R is the resistance.
• Superconductors:
  • These are materials that exhibit zero resistance below a critical temperature.
  • Superconductors are used in technologies like MRI machines and particle accelerators.

The correct answer is Option 2: V α I.

Key Points

• Ohm's Law states that the current (I) flowing through a conductor between two points is directly proportional to the voltage (V) across the two points, provided the temperature and other physical conditions remain constant.
• The mathematical representation of Ohm's Law is: V α I, which can also be written as V = IR, where R is the resistance.
• This principle is fundamental in electrical circuits and helps in calculating voltage, current, or resistance in a circuit.
• The unit of resistance (R) is the ohm (Ω), named after the German physicist Georg Simon Ohm, who first formulated the law.
• Ohm's Law is not applicable to non-linear components like diodes or transistors, where the relationship between voltage and current is not linear.

Additional Information

• Voltage (V):
  • Voltage is the electrical potential difference between two points in a circuit.
  • It is measured in volts (V) and is the driving force for current flow in a conductor.
• Current (I):
  • Current is the rate at which electric charge flows through a conductor.
  • It is measured in amperes (A) and flows from higher to lower potential in the circuit.
• Resistance (R):
  • Resistance is the property of a material that opposes the flow of electric current.
  • It depends on the material, length, cross-sectional area, and temperature of the conductor.
• Limitations of Ohm's Law:
  • Ohm's Law is valid only for linear, ohmic materials where the current and voltage have a proportional relationship.
  • It does not apply to materials like semiconductors or devices like LEDs, diodes, and transistors.
• Applications of Ohm's Law:
  • Used in designing electrical circuits and determining required resistor values.
  • Helps in analyzing and troubleshooting electrical and electronic systems.

The Correct answer is Rheostat.

Key Points

• A rheostat is an electrical device used to control the flow of current in a circuit by varying its resistance.
• It is commonly used as a variable resistor to adjust the intensity of current without interrupting the circuit.
• Rheostats are widely used in applications such as light dimming, motor speed control, and heater temperature regulation.
• The construction of a rheostat typically involves a coiled wire (resistance wire) and a sliding contact that adjusts the resistance by changing the length of the current path.
• Rheostats are versatile and can handle a wide range of current and voltage levels, making them suitable for industrial and laboratory use.
• The term "rheostat" originates from Greek words where "rheo" means "to flow" and "stat" means "to stop or control."

 Additional Information

• Voltmeter
  • A voltmeter is an instrument used to measure the voltage or potential difference across two points in an electrical circuit.
  • It must be connected in parallel to the circuit to avoid altering the flow of current.
  • Modern voltmeters are often digital and provide accurate readings of voltage in volts.
• Galvanometer
  • A galvanometer is a device used to detect and measure small electric currents.
  • It works on the principle of electromagnetic deflection, where a needle moves in response to current passing through a coil.
  • It is mainly used in laboratories and scientific experiments for detecting current flow.
• Ammeter
  • An ammeter is a device used to measure the amount of current flowing through a circuit.
  • It is connected in series to the circuit to measure current accurately.
  • Ammeter readings are expressed in units of amperes (A).