Electricity quiz

As the number of lamps increases, the current

• Increases

• Decreases

• Stayed the same

Answer explanation

In parallel combination, current increases as more lamps are added because the Voltage across the ends remain same but the resistance decreases.

As the number of lamps increased, the total resistance of the circuit

• Increases

• Decreases

• Stays the same

Answer explanation

Parallel combination of resistors reduces the effective resistance of the circuit

As the number of lamps increased, the potential difference across the battery

• Increased

• Decreased

• Stayed the same

Answer explanation

Potential difference remains constant for appliances connected in parallel combinations.

If the current in Ammeter A1 is 0.36A, Calculate the current flowing through A5

• 0.12 A

• 0.36 A

• 0.22

• 0.9 A

Answer explanation

It is 0.36 A, because A1 and A5 are in series combination

The resistance of one lamp is 15 Ω. The current in the lamp is 0.12 A. Calculate the power output of the lamp.

• 0.216 W

• 216 W

• 126 W

• 0.126 W

Answer explanation

Use P = I²R formula,

P = 0.12² * 15 = 0.216 W

The mean current from the solar cells to the battery is 3.5 A. Calculate the charge flow from the solar cells to the battery in 3600 seconds.

• 1,26,000 C

• 12,600 C

• 14400 C

• 98600 C

Answer explanation

Use Q = It formula,

Q = 3.5 * 3600,

Q = 12600 C

The battery in an electric car can store 162 000 000 J of energy. The charging station has a power output of 7200 W. Calculate the time taken to fully recharge the battery from zero.

• 24000 s

• 14400 s

• 21480 s

• 22500 s

Answer explanation

Energy = power x time taken

162 000 000 = 7200 × t

t = 22500 s

Which equation links current (I), potential difference (V) and resistance (R)?

• I = VR

• V = I²/R

• I = R/V

• V = IR

Answer explanation

Ohms law states that the potential difference(V) across the two ends of a conductor is directly proportional to the current (I) flowing through it, provided the temperature remains constant.

#To remove proportionality we use the constant called resistance (R)

V = IR

What is the unit of electrical resistance?

• Volt

• Ohm

• Ampere

• Watt

If a circuit has a total voltage of 12 V and a total resistance of 4 Ω, what is the total current flowing through the circuit?

• 3 A

• 6 A

• 12 A

• 48 A