Physics Quiz: Current Electricity Trivia Questions!

1. The material through which electric charge can flow easily is

Copper

Germanium

Quartz

Mica

Copper is a good conductor of electricity, meaning it allows electric charge to flow easily through it. This is due to its atomic structure, which allows for the movement of electrons. Copper is commonly used in electrical wiring and circuitry because of its high conductivity. Germanium, quartz, and mica are not as good conductors as copper, so they do not allow electric charge to flow as easily.

Explanation

Copper is a good conductor of electricity, meaning it allows electric charge to flow easily through it. This is due to its atomic structure, which allows for the movement of electrons. Copper is commonly used in electrical wiring and circuitry because of its high conductivity. Germanium, quartz, and mica are not as good conductors as copper, so they do not allow electric charge to flow as easily.

2. A toaster operating at 240V has a resistance of 120Ω. The power is

480 W

400 W

2 W

240 W

The power of an electrical device can be calculated using the formula P = V^2/R, where P is power, V is voltage, and R is resistance. In this case, the voltage is given as 240V and the resistance is given as 120Ω. Plugging these values into the formula, we get P = (240^2) / 120 = 480W. Therefore, the correct answer is 480W.

Explanation

The power of an electrical device can be calculated using the formula P = V^2/R, where P is power, V is voltage, and R is resistance. In this case, the voltage is given as 240V and the resistance is given as 120Ω. Plugging these values into the formula, we get P = (240^2) / 120 = 480W. Therefore, the correct answer is 480W.

3. The current flowing in a conductor is proportional to

Drift velocity

1/ area of cross section

1/no of electrons

Square of area of cross section.

The current flowing in a conductor is proportional to drift velocity because drift velocity is the average velocity at which free electrons move in a conductor due to an applied electric field. As more electrons move with a higher drift velocity, the overall current in the conductor increases. Therefore, the greater the drift velocity, the greater the current flowing in the conductor.

Explanation

The current flowing in a conductor is proportional to drift velocity because drift velocity is the average velocity at which free electrons move in a conductor due to an applied electric field. As more electrons move with a higher drift velocity, the overall current in the conductor increases. Therefore, the greater the drift velocity, the greater the current flowing in the conductor.

4. In the case of insulators, as the temperature decreases, resistivity

Increases

Becomes zero

Decreases

Remains constant

As the temperature decreases in the case of insulators, the resistivity increases. This is because insulators have a large energy band gap between their valence band and conduction band. At higher temperatures, more electrons are able to gain enough energy to jump from the valence band to the conduction band, allowing for better conductivity. However, as the temperature decreases, the number of electrons with enough energy decreases, leading to a decrease in conductivity and an increase in resistivity.

Explanation

As the temperature decreases in the case of insulators, the resistivity increases. This is because insulators have a large energy band gap between their valence band and conduction band. At higher temperatures, more electrons are able to gain enough energy to jump from the valence band to the conduction band, allowing for better conductivity. However, as the temperature decreases, the number of electrons with enough energy decreases, leading to a decrease in conductivity and an increase in resistivity.

5. When n resistors of equal resistances (R) are connected in series, the effective resistance is

NR

1/nR

R/n

N/R

When n resistors of equal resistances (R) are connected in series, the effective resistance is the sum of the resistances of all the resistors. Since all the resistors have the same resistance (R), the effective resistance would be n times the resistance of each resistor (R). Therefore, the correct answer is nR.

Explanation

When n resistors of equal resistances (R) are connected in series, the effective resistance is the sum of the resistances of all the resistors. Since all the resistors have the same resistance (R), the effective resistance would be n times the resistance of each resistor (R). Therefore, the correct answer is nR.

6. If the length of a copper wire has a certain resistance R, then on doubling the length its specific resistance

Will remain the same

Will be doubled

Will become 1/4 th

Will become 4 times

The specific resistance of a material is a constant property that depends on the material itself, not on its length. Therefore, doubling the length of a copper wire will not change its specific resistance.

Explanation

The specific resistance of a material is a constant property that depends on the material itself, not on its length. Therefore, doubling the length of a copper wire will not change its specific resistance.

7. When two 2Ω resistances are in parallel, the effective resistance is

1 Ω

2 Ω

0.5 Ω

4 Ω

When two resistances are in parallel, the effective resistance is given by the formula 1/Reff = 1/R1 + 1/R2. In this case, both resistances are 2Ω. Plugging in the values, we get 1/Reff = 1/2Ω + 1/2Ω = 2/2Ω = 1Ω. Therefore, the effective resistance when two 2Ω resistances are in parallel is 1Ω.

Explanation

When two resistances are in parallel, the effective resistance is given by the formula 1/Reff = 1/R1 + 1/R2. In this case, both resistances are 2Ω. Plugging in the values, we get 1/Reff = 1/2Ω + 1/2Ω = 2/2Ω = 1Ω. Therefore, the effective resistance when two 2Ω resistances are in parallel is 1Ω.

8. Charge of 60 C passes through an electric lamp in 2 minutes. Then the current in the lamp is

0.5 A

30 A

1 A

5A

The current in the lamp can be calculated by dividing the charge passing through it by the time taken. In this case, the charge is given as 60 C and the time is given as 2 minutes. Converting the time to seconds (2 minutes = 120 seconds), we can calculate the current as 60 C / 120 s = 0.5 A. Therefore, the current in the lamp is 0.5 A.

Explanation

The current in the lamp can be calculated by dividing the charge passing through it by the time taken. In this case, the charge is given as 60 C and the time is given as 2 minutes. Converting the time to seconds (2 minutes = 120 seconds), we can calculate the current as 60 C / 120 s = 0.5 A. Therefore, the current in the lamp is 0.5 A.

9. If the resistance of a coil is 2 Ω at

and α = 0.004 /, then its resistance at

is

2.8 Ω

0 Ω

1.4 Ω

4 Ω

The resistance of a coil is directly proportional to its temperature coefficient, which is represented by the symbol α. In this case, the temperature coefficient α is given as 0.004 /°C. Since the temperature is not provided in the question, we can assume that it remains constant. Therefore, if the resistance at is 2 Ω, the resistance at will be 2 Ω * (1 + α * ΔT), where ΔT is the change in temperature. Since ΔT is not given, we can assume it to be 0, which means there is no change in temperature. Therefore, the resistance at will be 2 Ω * (1 + 0.004 * 0) = 2 Ω. Thus, the correct answer is 2 Ω.

Explanation

The resistance of a coil is directly proportional to its temperature coefficient, which is represented by the symbol α. In this case, the temperature coefficient α is given as 0.004 /°C. Since the temperature is not provided in the question, we can assume that it remains constant. Therefore, if the resistance at is 2 Ω, the resistance at will be 2 Ω * (1 + α * ΔT), where ΔT is the change in temperature. Since ΔT is not given, we can assume it to be 0, which means there is no change in temperature. Therefore, the resistance at will be 2 Ω * (1 + 0.004 * 0) = 2 Ω. Thus, the correct answer is 2 Ω.

10. According to Faraday's law of electrolysis, when a current is passed, the mass of ions deposited at the cathode is independent of

Resistance

Time

Charge

Current

According to Faraday's law of electrolysis, the mass of ions deposited at the cathode is independent of resistance. This means that the amount of substance deposited during electrolysis is determined by the quantity of charge passing through the electrolyte, rather than the resistance of the circuit. In other words, the mass of ions deposited at the cathode is directly proportional to the amount of electric charge passing through the electrolyte, regardless of the resistance in the circuit.

Explanation

According to Faraday's law of electrolysis, the mass of ions deposited at the cathode is independent of resistance. This means that the amount of substance deposited during electrolysis is determined by the quantity of charge passing through the electrolyte, rather than the resistance of the circuit. In other words, the mass of ions deposited at the cathode is directly proportional to the amount of electric charge passing through the electrolyte, regardless of the resistance in the circuit.