challenging questions from pure physics

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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Name : ______________________ Class : _______________________

1. The diagram shows a boy on a swing which takes 40 s to make 10 complete swings.

What is the frequency of the oscillation?

A 0.25 Hz B 1.0 Hz C 4.0 Hz D 400 Hz

2. A pebble is dropped into still water so that circular wavefronts are seen to travel outwards with a speed v.

If the wavelength is , what is the time taken for the disturbance at P to reach Q ?

A / vB / (2v)C 3 / (2v)D 2 / v

3. Two rays of light are incident on a plane mirror.

Which diagram correctly shows the reflected rays?

1

P Q

A B

C D

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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4. The diagram shows a ray of light travelling from diamond to air.

The critical angle of the diamond is

A 22.0o

B 24.6o

C 28.2o

D 64.0o

5. An object is placed 20 cm from a converging lens and a real image is formed. The real image has the same size as the object. The object is now moved so that it is 18 cm from the lens.

Which of the following statements correctly describes the characteristics of the new image?

A It is larger and its distance from the lens is less than 20 cm.B It is larger and its distance from the lens is greater than 20 cm.C It is smaller and its distance from the lens is less than 20 cm.D It is smaller and its distance from the lens is greater than 20 cm.

6. The figure below shows the actual positions of the object PQ, the converging lens and the screen such that a sharp enlarged image is formed on the screen.

If the diagram is drawn full size, what is the focal length of the lens?

A 2.8 cm B 3.0 cm C 3.3 cm D 8.3 cm

2

object

screenP

Q

64o

22o

diamond

air

lens

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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7. The focal length of a thin converging lens is 10 cm. What is the maximum distance from the lens that the object can be placed so that the lens acts as a magnifying glass?

A 5 cmB 10 cm C 15 cmD 20 cm

8. Which of the following devices does NOT make use of electromagnetic waves in its operation?

A CameraB LoudspeakerC TV remote controlD Sun-tanning machine

9. Which of the following diagrams correctly shows the uniform electric field between two charged parallel metal plates?

10. An ammeter shows a reading of 25 mA. How much electrical charge flows through the ammeter in 10 seconds?

A 0.25 CB 2.5 C C 25 C D 250 C

11. The resistance of a cylindrical conductor of length L and cross-sectional area A is R. The resistance of another conductor made of the same material with length 2L and cross-sectional area 4A will be

A 0.125RB 0.5RC 2RD 8R

3

A B

C D

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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12. A circuit is set up as shown in the diagram below.

What is the reading shown on the voltmeter?

A 2.0 VB 3.0 VC 6.0 VD 10.0 V

13. The diagram below shows a circuit in which all the switches are open.

Which switch positions would give a resistance of 2.0 Ω between X and Y?

S1 S2 S3

A closed closed closed

B closed closed open

C closed open closed

D closed open open

4

X Y

3.0 Ω

6.0 Ω

S1

S2S3

4.5 Ω

V10

20 6V

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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14. Three identical resistors, with resistance R, are connected in a circuit as shown below.

Which of the following statements is not correct?

A I1 = I2

B I3 = 2 I2

C V3 = 2 V1

D V1 = ½ V2

15. Three identical light bulbs are connected to a constant-voltage d.c supply as shown in the diagram below. Each bulb operates at normal brightness and the ammeter registers a steady current.

The filament of one of the bulbs breaks. What happens to the ammeter reading and to the brightness of the remaining bulbs?

Ammeter reading Bulb brightness

A increases increases

B increases unchanged

C decreases unchanged

D decreases increases

5

R

R

R

I2

I1

I3

V1 V2

V3

A

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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16. A 3-way adapter is fitted into socket S. This enables a thermal boiler (2 kW), a heater (1 kW) and a cooker (0.8 kW) to operate at the same time.

If the mains supply is 200 V, what is the total current being drawn from the socket to the adapter when the three appliances are operated at the same time?

A 1.8 AB 9.0 AC 18 AD 19 A

17. Which of the following is a non-magnetic material?

A Copper B Iron C Steel D Nickel

18. The diagram below shows an electromagnet. The current flows from B to A along the wire.

What is the polarity of the electromagnet at end X and end Y?

X YA North NorthB North SouthC South NorthD South South

6

A

YX

B

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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19. Diagram 1 below shows the magnetic field near a bar magnet and a metal bar XY. In diagram 2, XY has been turned around.

Which of the following statements correctly describes bar XY?

A It is a magnet with the north pole at X.B It is a magnet with the north pole at Y.C It is a copper rod.D It is a soft iron rod.

20. The diagram shows a beam of electrons about to enter a magnetic field. The direction of the field is into the page.

What will be the direction of the deflection as the beam passes into the magnetic field?

A Towards the bottom of the page.B Towards the top of the page.C Into the page.D Out of the page.

7

X X X X X X

X X X X X X

X X X X X X

X X X X X X

magnetic field into the page

electron beam

diagram 1

X

Y

N

S

X

Y

diagram 2

N

S

Y

X

diagram 1

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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Structured Questions1. The figure below shows an electrical kettle and the live, neutral and earth wires of a

household electricity supply.

(a) Draw lines on the diagram to show how the kettle should be connected to the supply. Include a switch and a fuse in the diagram.

[2]

(b) Explain the importance of including the earth wire in the circuit.[2]

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(c) Explain why some appliances do not require an earth wire.[1]

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2. Three identical lamps, X, Y and Z are connected as shown.

8

live

neutral

earth

insulator

heating element

metal case

S Z

X

Y

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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What happens to the brightness of the lamps X and Y when the switch S is closed? Explain your answer. [3]

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3. (a) The figure below shows a door lock which can be opened only from the inside of a flat.

(i) Explain how the door is unlocked when the switch is closed. [2]

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9

metal bar fixed pivot

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

________________________________________________________________________________________________(ii) Why is the spring needed in the lock?

[1]

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(iii) Would the lock still work if the cells were reversed? Explain your answer.[1]

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4. Read the passage carefully and then answer the questions that follow.

The microwave ovenThe microwave oven is now commonly used in kitchens to quickly heat up pre-prepared and fresh food. It produces microwave radiation of frequency 2500 MHz that is absorbed by water molecules. The microwaves can only penetrate a short distance inside the food. The typical power in the microwave beam is 600 W. Over each distance of 3 mm, the power available from the microwave decreases by 60%. Thicker food can, however, be cooked in the microwave oven using processes other than the absorption of microwave energy.

(a) Microwave is a type of “transverse wave”. Define the term “transverse wave”. [1]

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(b) Calculate the wavelength of the microwaves used in the microwave oven. Take the speed of light as 3.0 x 108 m/s.

[2]

(c) State another application which uses microwave.[1]

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SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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5. A lamp L is placed at the bottom of a container with liquid. Fig. 5 shows the path of the light rays from the lamp. The refractive index of the liquid is 1.40.

(a) Define what is meant by critical angle. [1]

(b) Draw and complete the path of

(i) the ray LM if it meets the liquid-air boundary at an angle of incidence which is the same as the critical angle, [1]

(ii) the ray LK if it meets the liquid-air boundary at an angle of incidence which is greater than critical angle. [1]

(c) Calculate the angle of incidence of ray LQ at liquid-air boundary. [2]

angle of incidence =

12

L

MK125°

Q

Fig. 5

liquid

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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6. Fig. 6 shows a cathode-ray oscilloscope trace for a sound wave produced by a loudspeaker. The speed of sound in air is 330 m/s.

(a) Define the frequency of a wave. [1]

(b) It takes 0.02 s for the whole trace to be produced.

(i) Calculate the frequency of the sound produced by the loudspeaker. [1]

frequency =

(ii) Determine the wavelength in air of the sound produced by the loudspeaker. [2]

wavelength =

(c) (i) On Fig. 6, draw the trace for a louder sound with half the pitch. [1]

(ii) Explain the difference between the two traces. [2]

13

Fig. 6

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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7. (a) Fig. 10.1 shows a circuit with a battery and three resistors. The voltmeter V is of high resistance and the ammeters A1, A2 and A3 are of negligible resistance. The reading shown in A3 is 0.20 A.

Calculate

(i) the p.d. across the 6.0 resistor, [1]

p.d =

(ii) the current through the ammeter A2, [2]

current in A2 =

(iii) the current through the ammeter A1, [1]

current in A1 =

(iv) the reading of the voltmeter across the battery, [2]

voltmeter reading =

14

4.0

6.0

3.4

V

A1

A2

A3Fig. 10.1

SMK Negeri 11 Semarang Challenging Questions Drs. Pristiadi Utomo, M.Pd

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(b) Fig 10.2 shows the same electric kettle being connected to a 240 V mains supply by a flexible cable. The kettle has a power rating of 2 500 W.

Table 10.1 shows the maximum current that may be carried safely by wires of various diameters.

wire diameter/ mm maximum current/ A

0.50 3

0.75 6

1.00 10

1.25 13

1.50 15

(i) Calculate the current in the cable when the kettle is in use. [2]

current =

(ii) From the table, select the smallest diameter of wire that can be used safely for this kettle. [1]

diameter of wire =

(iii) Describe one fault that may occur in the flexible cable that will cause the fuse in the plug to melt. [1]

15

electric kettle

flexible cable

plug

Fig 10.2

240 V mains supply