A cell is connected to a lamp, as shown. A charge of 4.0 C flows through the lamp in 2.0 s. What is the direction of the electron flow in the lamp and what is the current in the lamp?
A direction of electron flow in lamp = from left to right; current /A = 2.0
B direction of electron flow in lamp = from left to right; current /A = 8.0
C direction of electron flow in lamp = from right to left; current /A = 2.0
D direction of electron flow in lamp = from right to left; current /A = 8.0
The four circuits shown all include an a.c. power supply, two diodes and a lamp.
In which circuit is there a rectified current in the lamp?
A
B
C
D
The diagram shows part of a circuit used to switch street lamps on and off automatically. In the evening it gets dark.
Which row shows the effect on the resistance of the light-dependent resistor (LDR) and on the potential difference (p.d.) across it?
A domestic circuit includes a 30 A fuse. This protects the wiring if there is too much current in the circuit.
In which wire is the 30 A fuse positioned, and what does it do when it operates?
A wire has a certain electrical resistance. The diameter and length of the wire may be changed.
Which pair of changes must cause the resistance of the wire to increase?
P and Q are the circuit symbols for two electrical components.
Which components are represented by P and by Q?
The diagram shows a battery connected to two resistors. Four students separately measure the electromotive force (e.m.f.) of the battery, the current in the resistors, and the potential difference (p.d.) across resistor R. Their results are shown in the table below the battery and resistors.
Which row shows values with their correct units?
A 3.0 Ω resistor and a 6.0 Ω resistor are connected in parallel.
What is their combined resistance?
A 0.50 Ω
B 2.0 Ω
C 4.5 Ω
D 9.0 Ω
Which circuit shows the directions of the conventional current I and the flow of electrons?
Four lamps are each labelled 240 V.
In which circuit do all four lamps have normal brightness?
A battery charger plugs into a 230 V a.c. supply. The charger is used to charge a 6.0 V d.c. battery. The charger contains diodes and a transformer.
What is the purpose of these components?
A diodes: rectify the a.c.; transformer: steps down the voltage
B diodes: rectify the a.c.; transformer: steps up the voltage
C diodes: step down the voltage; transformer: rectifies the a.c.
D diodes: step up the voltage ; transformer: rectifies the a.c.
The diagram shows a potential divider connected to two voltmeters P and Q. The resistance of the variable resistor is decreased.
Which row shows what happens to the reading on each voltmeter?
The diagram shows part of an electrical circuit. The current in the 4.0 Ω resistor is 3.0 A.
What is the current in the ammeter?
A 4.5 A
B 6.0 A
C 9.0 A
D 12.0 A
The circuit diagram shows a thermistor in a potential divider. A voltmeter is connected across the thermistor. The graph shows how the resistance of the thermistor changes with temperature.
As the thermistor becomes warmer, what happens to its resistance and what happens to the reading on the voltmeter?
The circuit diagram shows a 4.0 Ω resistor and an 8.0 Ω resistor connected to a 6.0 V battery.
What is the current in the battery?
A 0.50 A
B 0.75 A
C 1.5 A
D 2.0 A
The diagram shows a circuit which includes an uncharged capacitor and a switch. The switch can be moved between position X and position Y.
What happens to the capacitor when the switch is moved to position X, and what happens when the switch is then moved to position Y?
Por favor espera - en proceso…