P2 Revision Booklet

Energy in Circuits

Easy (Grade D/E)

Q1.          The diagram shows a helicopter being used to rescue a person from the sea.

(a)     (i)      The mass of the rescued person is 72 kg.
Use the equation in the box to calculate the weight of the rescued person.
 
weight    =    mass    ×    gravitational field strength	

gravitational field strength = 10 N/kg
Show clearly how you work out your answer.
...............................................................................................................
...............................................................................................................
                                          Weight = .................................................. N
(2)

(ii)     An electric motor is used to lift the person up to the helicopter.
The motor lifts the person at a constant speed.
State the size of the force, T, in the cable.
                                        Force T = .................................................. N
(1)

(b)     To lift the person up to the helicopter, the electric motor transformed 21 600 joules of energy usefully.
(i)      Use a form of energy from the box to complete the following sentence.
 
gravitational potential	heat	sound	

The electric motor transforms electrical energy to kinetic energy. The kinetic energy 
is then transformed into useful ..................................................... energy.
(1)

(ii)     It takes 50 seconds for the electric motor to lift the person up to the helicopter.
Use the equation in the box to calculate the power of the electric motor.

Show clearly how you work out your answer and give the unit.
Choose the unit from the list below.
 
coulomb (C)	hertz (Hz)	watt (W)	

...............................................................................................................
...............................................................................................................
                                              Power = ..................................................
(3)
(Total 7 marks)

 

Q2.          (a)     The diagram shows the circuit used by a student to measure the power of a filament lamp.

          Name a component connected in parallel with the filament lamp.
.....................................................................................................................................
(1)

(b)     By adding another component to the circuit, the student is able to obtain a range of ammeter and voltmeter readings.
 
Ammeter reading in amps 	Voltmeter reading in volts 	
0.10	1.0 	
0.15	2.0 	
0.20	4.0 	
0.25	7.0 	
0.30 	11.0 	

(i)      Which one of the following components did the student add to the circuit?
         Draw a ring around your answer.
                                   fuse                    switch            variable resistor
(1)

(ii)     What is the range of ammeter readings taken by the student?
from .............................. amps to .............................. amps
(1)

(iii)     Use the data in the table and the equation in the box to calculate the maximum power of the filament lamp.

         Show clearly how you work out your answer.
...........................................................................................................................
...........................................................................................................................
Power = .............................. W
(3)

(c)     Complete the following sentence by drawing a ring around the correct line in the box.
 	increases	
As the temperature of a filament lamp increases, its resistance	remains constant	
 	decreases	

(1)
(Total 7 marks)

 

Q3.          (a)     Complete the sentence below to name the instrument used to measure electrical current.
The instrument used to measure electrical current is called ......................................
(1)

(b)     In the diagram below each box contains an electrical component or a circuit symbol. 
Draw straight lines to link each electrical component to its circuit symbol. The first one has been done for you.

(4)
(Total 5 marks)

 

Q4.          The diagram shows an electrical circuit.

(a)     Complete the two labels on the diagram.
(2)
(b)     P and Q are meters.
What is meter P measuring? .......................................................................................
What is meter Q measuring? .......................................................................................
(2)
(Total 4 marks)

 

Energy in circuits- Mark scheme

M1.         (a)      (i)     720
allow 1 mark for correct substitution,
ie 72 × 10 provided no subsequent step shown
2

(ii)     720ortheir (a)(i)
1

(b)     (i)      gravitational potential 
allow gravitational
allow potential
1

(ii)     432
allow 1 mark for correct substitution, ie  provided no subsequent step shown
2

watt / W
1
[7]

M2.          (a)     voltmeter
and no other
do not accept voltage
1

(b)     (i)      variable resistor
1
(ii)     0.10 – 0.30
accept 0.1 – 0.3
accept 0.3 – 0.1
accept 0.30 – 0.10
1

(iii)     3.3 (W)
allow 1 mark for correct data choice
allow 2 marks for substitution of correct
data i.e. 0.30 × 11.0
the following answers gain 2 marks
0.10 / 0.30 / 0.80 / 1.75
allow 1 mark for substitution of incorrect
of data incorrectly calculated e.g.
0.20 × 4.0 = 0.6 scores 1 mark
3

(c)     increases
1
[7]

 

M3.          (a)     ... ammeter
for 1 mark
1

(b)     5 right
gains 4 marks
          4 right
gains 3 marks
          3 right
gains 2 marks
          2 right
gains 1 mark
4
[5]

 

M4.          (a)     (i)      diode
[Do not accept ‘rectifier’ or LED] 
(ii)     lamp / bulb / light
each for 1 mark
2
(b)     •        P = voltage / potential difference / p.d. / volts / V
[Allow ‘Voltmeter]
•        Q = current / amperes / amps / A
[Allow ‘ammeter]
each for 1 mark
2
[4]