# Current Electricity MCQs

## When current is flowing in a superconductor, which statement is not true?

• A. A battery is needed to keep the current going.
• B. Electrical charges are moving
• C. The resistance is zero.
• D. No power is given off in the form of heat.

## When a superconductor’s temperature drops below the critical temperature, its resistance:

• A. equals that of a semiconductor of equal dimensions.
• B. increases by two
• C. drops to zero.
• D. reduces to one half.

## Superconductivity was discovered by:

• A. Volta
• B. Ohm
• C. Onnes.
• D. Bednorz and Müller.

## Consider some material that has been cooled until it has become a superconductor. If it is cooled even further its resistance will:

• A. increase.
• B. decrease
• C. stay constant and zero.
• D. None of the above.

• A. 300 kWh
• B. 480 kWh
• C. 690 kWh
• D. 840 kWh

## Which process will double the power given off by a resistor?

• A. doubling the current while doubling the resistance
• B. doubling the current by making a resistance half as big
• C. doubling the current by doubling the voltage
• D. doubling the current while making the voltage half as big

## Light bulb A is rated at 60 W and light bulb B is rated at 100 W. Both are designed to operate at 110 V. Which statement is correct?

• A. The 60 W bulb has a greater resistance and greater current than the 100 W bulb.
• B. The 60 W bulb has a greater resistance and smaller current than the 100 W bulb.
• C. The 60 W bulb has a smaller resistance and smaller current than the 100 W bulb.
• D. The 60 W bulb has a smaller resistance and greater current than the 100 W bulb.

## A cook plugs a 500 W crockpot and a 1 000 W kettle into a 240 V power supply, all operating on direct current. When we compare the two, we find that

• A. Icrockpot < Ikettle and Rcrockpot < Rkettle.
• B. Icrockpot < Ikettle and Rcrockpot > Rkettle.
• C. Icrockpot = Ikettle and Rcrockpot = Rkettle.
• D. Icrockpot > Ikettle and Rcrockpot < Rkettle.

• A. V A
• B. V/s
• C. V Ω
• D. A Ω