Chapter 15 Direct Current Circuits

A circuit is set up as shown in the diagram. The e.m.f. of the battery is 1.5 V and the resistance R is 2.0  $\Omega$ . Which statement below is not true about the circuit?

• When switch S is opened, the voltmeter reads 1.5 V.

• When switch S is closed, the voltmeter reads less than 1.5 V.

• When switch S is closed, the ammeter reads 0.75 A.

• When switch S is opened, the ammeter reads zero.

In a circuit, the current flow is 1.0 A. If the potential difference across the resistor is 1.0 V and the e.m.f. of the cell is 1.5 V, what is the internal resistance of the cell?

• 0.2 $\Omega$

• 0.5 $\Omega$

• 1.2 $\Omega$

• 1.5 $\Omega$

The cells in the above circuits have internal resistance 1.0 $\Omega$ and all the bulbs are identical. Which circuit has the highest ammeter reading?

• A

• B

• C

• D

Three identical cells each of e.m.f. 1.5 V and internal resistance 0.5 $\Omega$ are connected to a resistor of resistance 6 $\Omega$ as shown in the diagram. Which statement below is not true about the circuit?

• The voltmeter reads a value less than the total e.m.f. of the cells.

• The voltmeter reads the potential difference across the 6 $\Omega$ resistor.

• The effective e.m.f. of the cells is equal to the e.m.f. of one cell.

• The power dissipated in overcoming the internal resistance of the three cells is 0.24 W.

One part of a circuit is as shown in the diagram. If the current flowing in the circuit is 2 mA and the potential at point P is 12 V, find the potential at point R.

• 0 V

• 2 V

• 4 V

• 8 V

• A

• B

• C

• D

An electric circuit is as shown in the diagram. If cell P and cell Q have e.m.f. 3 V and 4 V with internal resistance 1 $\Omega$  and 2 $\Omega$ respectively, calculate the current flowing in the circuit.

• 0.20 A

• 0.50 A

• 1.0 A

• 1.2 A

• A

• B

• C

• D

• 1000 $\Omega$

• 2000 $\Omega$

• 3000 $\Omega$

• 5000 $\Omega$

• 4.0 V

• 5.0 V

• 8.0 V

• 10 V