SPH3U Electricity Quiz

Front

Work done in moving 5.0 C against 12 V

Back

60 J

Answer explanation

The work done (W) is calculated using the formula W = Q × V, where Q is charge in coulombs and V is potential difference in volts. Here, W = 5.0 C × 12 V = 60 J. Thus, the correct answer is 60 J.

Front

Energy used by a device (1.5V, 0.20A, 60s)

Back

18 J

Answer explanation

To find the energy used, use the formula: Energy (J) = Voltage (V) x Current (A) x Time (s). Here, Energy = 1.5 V x 0.20 A x 60 s = 18 J. Thus, the correct answer is 18 J.

Front

Current in electric circuit with 10 C in 5 s

Back

2.0 A

Answer explanation

Current (I) is calculated using the formula I = Q/t, where Q is charge in coulombs and t is time in seconds. Here, I = 10 C / 5.0 s = 2.0 A. Thus, the correct answer is 2.0 A.

Front

Current: 2.0 A

Back

Electrons in 1 second: 1.3 x 10^19

Answer explanation

To find the number of electrons, use the formula: number of electrons = current (A) x time (s) x charge of an electron (1.6 x 10^-19 C). Thus, 2.0 A x 1.0 s / (1.6 x 10^-19 C) = 1.25 x 10^19, approximately 1.3 x 10^19.

Front

Effect of temperature on electrical resistance

Back

Increases

Answer explanation

As the temperature of the copper wire increases, its electrical resistance also increases due to the increased vibrations of the atoms, which impedes the flow of electrons. Therefore, the correct answer is that the resistance increases.

Front

Resistance of wire

Back

Directly with length, inversely with cross-sectional area

Answer explanation

The resistance of a wire increases with length (directly) and decreases with cross-sectional area (inversely). Therefore, longer cords require thicker wires to reduce resistance, making the correct choice "directly with length and inversely with cross-sectional area."

Front

Insert between A and B:

Back

source of potential difference

Answer explanation

To establish a steady electric current between points A and B, a source of potential difference (like a battery) must be inserted. This provides the necessary voltage to drive the current through the circuit.

Front

Voltage decrease from 12V to 6V

Back

Current is halved

Answer explanation

According to Ohm's Law (V = IR), when the voltage decreases from 12 V to 6 V, the current (I) is halved. With a 6.0-ohm resistor, I = V/R, so I at 12 V is 2 A and at 6 V is 1 A, confirming the current is halved.

Front

Resistance of a 110V heater drawing 2.0A

Back

55 ohms

Answer explanation

To find the resistance (R) of the heater, use Ohm's Law: R = V/I. Here, V = 110 volts and I = 2.0 amperes. Thus, R = 110/2 = 55 ohms. Therefore, the resistance of the heater is 55 ohms.

Front

Electrical energy delivered to immersion heater

Back

9.0 x 10^3 J

Answer explanation

The energy delivered is calculated using the formula E = I^2 * R * t. Here, E = (3.0 A)^2 * (5.0 ohms) * (200 s) = 9.0 x 10^3 J. Thus, the correct answer is 9.0 x 10^3 J.