Cambridge IGCSE Physics - 0625 - Core Paper 3 2016 Summer Zone 2

(a) Name the quantity that the student is measuring with the rule.
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(b) The student uses a digital stopwatch to measure the time between the drops of water. She repeats her measurement.

Fig. 1.2 shows the reading on the stopwatch for all her measurements.



(i) On the line below each stopwatch, record the time, in seconds, measured by the student. [1]

time = .................... s
time = .................... s
time = .................... s

(ii) Calculate the average time between drops of water. Show your working.

average time between drops = ........................................................ s [2]

(c) The student collects drops of water for 15.5 minutes.

Calculate how many drops leave the tap in 15.5 minutes. Use your answer to part b(ii).

number of drops = ................................................................. [3]

(a) Calculate the distance he travels in the first 10s.

distance = .................................................... m [3]
(b) Fig. 2.2 shows three pairs of forces A, B and C.

Identify which pair of forces, A, B or C, acts on the cyclist between 11s and 16s. Explain your choice.
pair of forces .................................................................................................
explanation ....................................................................................................
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(c) The cyclist pushes on one pedal with a force of 120N. The area of his shoe in contact with the pedal is 16cm$^2$.
Calculate the pressure on the pedal. Include the unit.
pressure = .................................................... [4]

Fig. 3.1 shows a girl and a boy on a see-saw.


The see-saw pivots on the log.
(a) Calculate the girl's moment about the pivot.

$\text{girl's moment} = \text{................................................} \text{ Nm [2]}$

(b) The see-saw is balanced horizontally.
Calculate the weight $W$ of the boy.

$\text{weight of boy} = \text{........................................................} \text{ N [3]}$

A student is investigating a mixture of water and ice. The water and ice are at the same temperature. He uses a thermometer.

(a) Fig. 4.1 shows a thermometer.



(i) On Fig. 4.1, label X and Y. [2]

(ii) The thermometer is put into the mixture of water and ice. On Fig. 4.2, draw an arrow pointing to the reading on the scale. [1]



(b) The beaker of ice and water is left in a warm room for five hours.

State what happens to the ice during this time. Describe this process in terms of the molecules in the ice. [4]

Fig. 5.1 shows two circuits, A and B.



Both circuits contain a 6V power supply and two 6V lamps.

(a) State two advantages of circuit B compared to circuit A.
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(b) Fig. 5.2 shows the energy input and outputs, in one second, for one electric lamp.



(i) Calculate the useful energy output, in one second, of the lamp.
useful energy output = ...........................................................J [1]

(ii) In the space below draw a labelled diagram, similar to Fig. 5.2, for a more efficient lamp. [1]

(c) Electricity can be generated using wind turbines.



State two advantages and two disadvantages of using wind turbines, rather than fossil fuels, to generate electricity.
advantages ...................................................................................................................
................................................................................................................... ................................................................................................................... ...................................................................................................................

disadvantages .............................................................................................................
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Fig. 6.1 shows the regions of the electromagnetic spectrum. Two regions have not been named.


Fig. 6.1
(a) Complete Fig. 6.1 by labelling the two regions that have not been named. [2]
(b) On Fig. 6.1, circle the region with the longest wavelength. [1]
(c) (i) Suggest a use for gamma radiation.
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(ii) Suggest a use for ultraviolet radiation.
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Fig. 7.1 shows a ray of light incident on a rectangular glass block at point X.
!
The ray of light is refracted at X.
On Fig. 7.1,
(a) draw the normal at X, [1]
(b) draw the path of the ray through the glass block until it reaches the surface RS, [1]
(c) label, at X, the angle of incidence with a letter $i$ and the angle of refraction with a letter $r$, [2]
(d) draw the path of the ray of light leaving the glass block. [1]

Researchers have found that the best temperature for drinking coffee is 60°C.
A designer has developed a new type of cup for keeping coffee at 60°C. The cup is shown in Fig. 8.1.

Material Z has a melting point of 60°C. At room temperature, material Z is solid.
Coffee, at a temperature of 90°C, is poured into the cup. The coffee cools rapidly to 60°C.
(a) State what happens to material Z when the hot coffee is poured into the cup.
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(b) Explain how the features of the cup enable the coffee to be kept at 60°C for a long time.
plastic lid .................................................................................................................................
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vacuum ....................................................................................................................................
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shiny outer steel wall .............................................................................................................
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material Z .................................................................................................................................. [5]
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(a) The resistance of a long piece of wire is 6.0 $\Omega$. The potential difference across the wire is 2.0 V.
Calculate the current in the wire.

current = ..................................................... A [3]

(b) A force acts on a wire carrying a current in a magnetic field.

Fig. 9.1 shows the direction of the current in the wire and the direction of the force acting on the wire.



(i) On Fig. 9.1, draw arrows to indicate the direction of the magnetic field. [1]
(ii) The magnetic field is reversed.

State what happens, if anything, to the direction of the force on the wire.
............................................................ [1]

(c) Fig. 9.2 shows a current-carrying coil in a magnetic field.



The coil starts to turn about its axle.

(i) State two ways of increasing the turning effect on the coil.
1. .................................................................
2. ................................................................. [2]

(ii) Describe and explain the effect of reversing the connections to the battery.
.................................................................
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Fig. 10.1 shows the charger for a laptop computer.

The charger contains a transformer.
(a) The voltage across the primary coil of the transformer is 230V.
The primary coil has 4995 turns and the secondary coil has 555 turns.
Calculate the output voltage of the transformer.
output voltage = .................................................. V [3]
(b) State the term used to describe this type of transformer.
........................................................................................ [1]

(a) Any atomic nucleus can be represented as $^{A}_{Z}X$.
(i) State which letter, A, X or Z, is the

• chemical symbol, ...........................
• nucleon number, ...........................
• proton number. ...........................

(a) A radioactive nucleus decays by the emission of a $\beta$-particle.
State what a $\beta$-particle is and give its charge.
............................................................................................................................................................................................
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(b) The graph in Fig. 12.1 shows how the count rate from a sample of a radioactive substance varies with time.
[Image_1: Graph showing count rate vs time]
Use the graph to find the half-life. Show your working on the graph.
half-life = .................................................... days [2]
(c) Following an accident, the soil around a nuclear power station is contaminated by caesium-137, which is radioactive.
A sample of this soil containing caesium-137 has a count rate of 180 counts/min. Caesium-137 has a half-life of 30 years and decays by $\beta$-emission.
(i) Calculate the count rate from the caesium-137 in the sample after 60 years.
count rate = .................................................... counts/min [2]
(ii) Suggest why people do not want to live near the power station, even after it has closed.
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