Self test for electricity: Electric circuits

Choose the correct answer for each question.


1.	Which of the following expressions is not a unit of electric quantity?
		Watt (W)
		Joule/second (J/s)
		Newton.second (Ns)
		Ampere (A)
		Volt (V)

2.	What are the units for current, voltage and resistance respectively?
		Ampere, Volt, Ohm
		Volt, Ampere, Ohm
		Ohm, Volt, Ampere
		Ampere, Ohm, Volt
		None of the above

3.	Which of the following expressions is correct? I = current, P = power, R = resistance, V = voltage
		R = IV
		I = RV
		P = RV
		V = IR
		P = IR

For Q4 to Q6, please refer to the following figure.
4.	If each of the bulbs has resistance = 1, then the current flow through B is:
		0.5 A
		0.75 A
		1 A
		1.33 A
		2 A.

5.	The voltage across A is:
		1 V
		1.33 V
		2 V
		2.67 V
		4 V

6.	If bulb B burns out, the current flow through C is:
		1 A
		2 A
		3 A
		4 A
		No current flows through the circuit

7.	There are 6 10²⁸ free electrons in a metal wire with cross section area = 5 mm². If the current through the wire is 2.5 A, what is the drift velocity of electrons?
		188496 m/s
		75400 m/s
		1.3310^-5 m/s
		5.210^-5 m/s
		Cannot be determined

For Q8 toQ10, please refer to the following figure.
8.	If all the switches are closed, the equivalent resistance of the circuit is:
		Cannot be determined
		0.545
		1
		1.833
		6

9.	The voltage across A is:
		1 V
		2 V
		3 V
		5 V
		6 V

10.	If switch C is opened, the current flows through B is:
		2 A
		3 A
		4 A
		6 A
		No current flows

11.	If the length of a metal wire is doubled, assuming that the cross section area and the resistivity remain unchanged, the resistance of the metal wire is:
		The same as before
		Half of the original one
		Twice of the original one
		Four times of the original one
		Cannot be determined

12.	When two identical light bulbs, each with resistance 2, are connected in series and a 4 V voltage is supplied. The power consumption of each bulb is
		1W
		2 W
		4 W
		8 W
		16 W

13.	Referring to Q12, if the bulbs is now connected in parallel, then the power consumption of each bulb is:
		1 W
		2 W
		4 W
		8 W
		16 W

For Q14 toQ16, please refer to the following figure.
14.	The resistance across AB is:
		0
		0.67
		0.73
		0.91
		2.4

15.	The resistance across AC is
		0
		0.7
		1.7
		2.4
		6

16.	The resistance across AD is
		0
		0.7
		0.9
		2.4
		6

17.	If the voltage across a device is measured, which of the following equipments should be used?
		Ammeter
		Galvanometer
		Ohmmeter
		Voltmeter
		None of the above

18.	Which of the following sentences is correct?
		A shunt is a small resistance that is connected in parallel with a galvanometer or an ammeter.
		A shunt is a small resistance that is connected in series with a galvanometer or an ammeter.
		A shunt is a large resistance that is connected in series with a galvanometer or an ammeter.
		A shunt is a large resistance that is connected in parallel with a galvanometer or a voltmeter.
		A shunt is a large resistance that is connected in series with a galvanometer or a voltmeter.

19.	Which of the following sentences about the multimeter is/are correct?
		Multimeter can be used to measure the current of the devices.
		Multimeter can be used to measure the voltage of the devices.
		Multimeter can be used to measure the resistance of the devices.
		Multimeter provides various range of scale for easy measurement.
		All of the above

20.	If a small resistance is measured, which of the following connection methods should be used?
		The ohmmeter with a small internal resistance should be connected in series with the unknown resistance of the device.
		The ohmmeter with a small internal resistance should be connected in parallel with the unknown resistance of the device.
		The ohmmeter with a large internal resistance should be connected in series with the unknown resistance of the device.
		The ohmmeter with a large internal resistance should be connected in parallel with the unknown resistance of the device.
		None of the above