Two parallel metal plates, a distance of 2 mm apart, have a potential difference of 1000 V across them.
What is the electric field strength between the plates?
Answer
A 500 V m^–1
B 50 000 V m^–1
C 50 000 N C^–1
D 500 000 N C^–1
Question 2
Question
The diagrams show two different circuits.
The cells in each circuit have the same electromotive force and zero internal resistance. The three resistors each have the same resistance R.
In the circuit on the left, the power dissipated in the resistor is P.
What is the total power dissipated in the circuit on the right?
The charge that an electric battery can deliver is specified in ampere-hours.
For example, a battery of capacity 40 ampere-hours could supply, when fully charged, 0.2 A for 200 hours.
What is the maximum energy that a fully charged 12 V, 40 ampere-hour battery could supply?
Answer
A 1.7 kJ
B 29 kJ
C 1.7 MJ
D 29 MJ
Question 4
Question
A battery with e.m.f. E and internal resistance r is connected in series with a variable external resistor.
The value of the external resistance R is slowly increased from zero.
Which statement is correct? (Ignore any temperature effects.)
A The potential difference across the external resistance decreases.
B The potential difference across the internal resistance increases.
C The power dissipated in r increases and then decreases.
D The power dissipated in R increases and then decreases.
Question 5
Question
A wire RST is connected to another wire XY as shown.
Each wire is 100 cm long with a resistance per unit length of 10 Ω/m.
What is the total resistance between X and Y?
Two lamps are connected in series to a 250 V power supply. One lamp is rated 240 V, 60 W and the other is rated 10 V, 2.5 W.
Which statement most accurately describes what happens?
Answer
A Both lamps light at less than their normal brightness.
B Both lamps light normally.
C Only the 60 W lamp lights.
D The 10 V lamp blows.
Question 7
Question
The wire of a heating element has resistance R. The wire breaks and is replaced by a different wire.
Data for the original wire and the replacement wire are shown in the table.
What is the resistance of the replacement wire?
In the circuit below, P is a potentiometer of total resistance 10 Ω and Q is a fixed resistor of resistance 10 Ω . The battery has an electromotive force (e.m.f.) of 4.0 V and negligible internal resistance. The voltmeter has a very high resistance.
The slider on the potentiometer is moved from X to Y and a graph of voltmeter reading V is plotted against slider position.
Which graph would be obtained?
Two electrically-conducting cylinders X and Y are made from the same material.
Their dimensions are as shown in the image.
The resistance between the ends of each cylinder is measured.
What is the ratio resistance of X/ resistance of Y?
Four resistors of resistance R, 2R, 3R and 4R are connected to form a network.
A battery of negligible internal resistance and a voltmeter are connected to the resistor network as shown.
The voltmeter reading is 2 V.
What is the electromotive force (e.m.f.) of the battery?
A Each coulomb of charge from the battery supplies 9.0 J of electrical energy to the whole
circuit.
B The battery supplies 9.0 J to an external circuit for each coulomb of charge.
C The potential difference across any component connected to the battery will be 9.0 V.
D There will always be 9.0 V across the battery terminals.
Question 14
Question
A pencil is used to draw a line of length 30 cm and width 1.2 mm. The resistivity of the material in the pencil is 2.0 × 10^–5
Ω m and the resistance of the line is 40 k Ω .
What is the thickness of the line?
Answer
A 1.25 × 10^–10 m
B 1.25 × 10^–8 m
C 1.25 × 10^–7 m
D 1.25 × 10^–5 m
Question 15
Question
A conductor consists of three wires connected in series. The wires are all made of the same metal but have different cross-sectional areas. There is a current I in the conductor.
Point Y on the conductor is at zero potential.
Which graph best shows the variation of potential V with distance along the conductor?
The graph shows how the electric current I through a conducting liquid varies with the potential
difference V across it.
At which point on the graph does the liquid have the smallest resistance?
The combined resistance R T of two resistors of resistances R 1 and R 2 connected in parallel is given by the formula shown.
1/RT = 1/R1 + 1/R2
Which statement is used in the derivation of this formula?
Answer
A The currents through the two resistors are equal.
B The potential difference across each resistor is the same.
C The supply current is split between the two resistors in the same ratio as the ratio of their
resistances.
D The total power dissipated is the sum of the powers dissipated in the two resistors
separately.
Question 18
Question
In the potentiometer circuit shown, the reading on the ammeter is zero.
The light-dependent resistor (LDR) is then covered up and the ammeter gives a non-zero reading.
Which change could return the ammeter reading to zero?
A battery of negligible internal resistance is connected to a resistor network, an ammeter and a switch S, as shown.
When S is open, the reading on the ammeter is 250 mA.
When S is closed, what is the change in the reading on the ammeter?
A charge of 7.5 C flows through a resistor in 5.0 s. A student has ammeters with different ranges that he can use to measure the current in the resistor.
Which ammeter range is the most appropriate?
Answer
A 0 - 1 A
B 0 - 2 A
C 0 - 5 A
D 0 - 40 A
Question 23
Question
Three identical cells are connected in parallel to a resistor.
What is the advantage of using three cells in parallel, rather than using a single cell?
Answer
A Each cell produces more energy.
B Each cell supplies more charge.
C Each cell takes longer to run down.
D The total electromotive force (e.m.f.) is larger.
Question 24
Question
When the flash on a camera is used, a charge of 1.5 C flows through the flash-tube in 0.0030 s. The average voltage across the flash-tube is 3600 V.
What is the electrical energy supplied to the flash-tube and what is the average power supplied?
Answer
A Energy = 2400 J; Power = 7.2 W
B Energy = 2400 J; Power = 800 000 W
C Energy = 5400 J; Power = 16.2 W
D Energy = 2400 J; Power = 1.8 x 10^6 W
Question 25
Question
The diagram shows a circuit. Which circuit diagram shows this circuit?
Two straight electrical conductors are parallel to one another. Each carries a current, one into the plane of the paper and one out of the plane of the paper.
Which diagram shows the magnetic field around the two wires?
The diagrams below show connected wires which carry currents I1, I2, I3 and I4.
The currents are related by the equation I1 + I2 = I3 + I4.
To which diagram does this equation apply?
A copper wire of cross-sectional area 2.0 mm^2 carries a current of 10 A. How many electrons pass through a given cross-section of the wire in one second?
Answer
A 1.0 x 10^1
B 5.0 x 10^6
C 6.3 x 10^19
D 3.1 x 10^25
Question 31
Question
The I-V characteristics of two electrical components P and Q are shown at left.
Which statement is correct?
In the circuit shown, P is a potentiometer of total resistance 10 Ω and Q is a fixed resistor of resistance 10 Ω. The battery has an e.m.f. of 4.0 V and negligible internal resistance. The voltmeter has a very high resistance. The slider on the potentiometer is moved from X to Y and a graph of voltmeter reading V is plotted against slider position.
Which graph is obtained?
A cell is connected in series with a 2.0 Ω resistor and a switch. The voltmeter is connected across the cell and reads 12 V when the switch is open and 8.0 V when the switch is closed.
What is the internal resistance of the cell?
A resistor has a resistance R. The potential difference across the resistor is V. Which of the following gives the energy dissipated in the resistor in time t?