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Physics — Model Question Paper 1

Physics · Kerala SSLC (Class 10) · English Medium · SSLC 2027 pattern · English Medium · 40 marks · 90 min + 15 min cool-off

Section A

Questions 1–4 carry 1 score each. Answer all.

  1. A stage light gives red light. A second light is to be added so that, where the two beams overlap on a white screen, the patch looks white. Which colour of light should the second lamp give? [1 mark]
    • Green
    • Blue
    • Cyan
    • Magenta
  2. Statement: In a small classroom, a clap does not produce a separately heard echo. Reason: The sensation of a sound persists in our ear for about 1/10 of a second, so the reflected sound must reach us at least 1/10 s after the original sound to be heard separately. [1 mark]
    • Both the Statement and the Reason are correct, and the Reason explains the Statement.
    • Both the Statement and the Reason are correct, but the Reason does not explain the Statement.
    • The Statement is correct, but the Reason is wrong.
    • The Statement is wrong, but the Reason is correct.
  3. Consider these statements about levers: (i) In a second order lever, the load is between the fulcrum and the effort. (ii) The mechanical advantage of a third order lever is always less than 1. (iii) A pair of scissors is a second order lever. (iv) The mechanical advantage of a first order lever can be greater than, equal to or less than 1. Which of these are correct? [1 mark]
    • (i) and (iii) only
    • (i), (ii) and (iv) only
    • (ii) and (iii) only
    • (i), (iii) and (iv) only
  4. Match Column I with Column II and choose the correct option. Column I: A. AC generator B. DC generator C. Step-down transformer Column II: P. Split rings Q. More turns in the primary coil than in the secondary R. Slip rings [1 mark]
    • A-P, B-R, C-Q
    • A-R, B-P, C-Q
    • A-R, B-Q, C-P
    • A-Q, B-P, C-R

Section B

Questions 5–11 carry 2 scores each. Questions 7 and 10 have a choice — answer (A) or (B).

  1. An optician's prescription for a pair of spectacles says: power = −2.5 D. [2 marks]
    • (a) Is the lens convex or concave? Find its focal length.
    • (b) A ray of light travelling parallel to the principal axis falls on this lens. How does it travel after refraction?
  2. A straight vertical wire passes through a hole in a horizontal sheet of cardboard. A strong current flows upward through the wire, and iron filings are sprinkled on the card. [2 marks]
    • (a) Name and state the rule used to find the direction of the magnetic field around the wire.
    • (b) Seen from above the card, are the magnetic field lines clockwise or anticlockwise? What happens to this direction if the current is reversed?
  3. (A) An electric kettle is marked 1500 W, 230 V. A family uses it for 20 minutes every day. [2 marks]
    • (a) What does the marking 1500 W, 230 V mean?
    • (b) How many units of electric energy does the kettle consume in 30 days?

    OR

    (B) Electricity bills can be reduced by choosing appliances and timings wisely.

  4. Answer the following about household wiring. [2 marks]
    • (a) Why are fuses and MCBs always connected in the phase line and not in the neutral line?
    • (b) An MCB and an RCCB are both used in the distribution board. How do their jobs differ?
  5. Workers push a 900 N barrel up a smooth plank 6 m long onto a lorry whose platform is 1.5 m high. [2 marks]
    • (a) Calculate the mechanical advantage of the plank used as an inclined plane.
    • (b) What is the least effort needed along the plank? Will using a 9 m plank make the job easier or harder?
  6. (A) The figure shows how the air pressure varies with distance along a sound wave at one instant. P and Q are two neighbouring points of maximum pressure, 0.68 m apart. The speed of sound in air is 340 m/s. [2 marks]
    • (a) Find the frequency of the sound. Can a human hear it?
    • (b) If the frequency of the source is doubled, what will be the new wavelength in the same air?

    OR

    (B) A radio set picks up only the station whose frequency matches the frequency to which its circuit is tuned.

  7. Ammu's 68-year-old grandfather could read easily when he was younger. Now he still sees distant buses clearly, but he cannot read a newspaper held 25 cm from his eyes. His near point has moved to 60 cm. This defect has developed with age. [2 marks]
    • (a) Name this defect of vision. What causes it?
    • (b) Which type of lens will help him read? Why?

Section C

Questions 12–17 carry 3 scores each. Questions 14 and 17 have a choice — answer (A) or (B).

  1. A ship uses SONAR to measure the depth of the sea. A pulse sent straight down returns after 1.2 s. (Speed of sound in sea water = 1480 m/s.) [3 marks]
    • (a) Why is ultrasound, and not audible sound, used in SONAR?
    • (b) Calculate the depth of the sea at that place.
    • (c) The ship moves to a place where the sea is 1110 m deep. After how much time will the echo be received?
  2. The heating coil of a room heater has a resistance of 46 Ω and works on a 230 V supply. [3 marks]
    • (a) Find the current through the coil and the power of the heater.
    • (b) Calculate the heat produced in 10 minutes.
    • (c) The coil is replaced by one of half the resistance and used on the same 230 V supply. Will the heat produced in 10 minutes increase or decrease? Justify.
  3. (A) An object 4 cm tall is placed 15 cm in front of a convex lens of focal length 10 cm. [3 marks]
    • (a) Using the Cartesian sign convention, find the position of the image.
    • (b) Find the magnification and the height of the image. Write the nature of the image.

    OR

    (B) Answer these about optical instruments that use lenses.

  4. A horizontal wire carries a current from west to east. It lies in a magnetic field that points vertically downward. [3 marks]
    • (a) State Fleming's left hand rule.
    • (b) In which direction will the wire experience a force?
    • (c) In a moving coil loudspeaker, how is this effect used to produce sound?
  5. Answer the following about colours. [3 marks]
    • (a) A red rose with green leaves is seen in a dark room lit only by pure green light. What colours do the petals and the leaves appear?
    • (b) Red and blue lights overlap on a white screen. Name the colour formed and its complementary colour.
    • (c) To an astronaut in space, the sky looks black even when the Sun is shining. Why?
  6. (A) A mobile charger has a transformer that changes 230 V AC to 11.5 V AC. Its primary coil has 2000 turns. (Assume no power loss.) [3 marks]
    • (a) Is it a step-up or step-down transformer? Find the number of turns in the secondary coil.
    • (b) If the secondary current is 2 A, find the current in the primary.
    • (c) Why will this transformer not work if it is connected to a 12 V battery?

    OR

    (B) A generator in a small hydroelectric plant produces electricity when its armature is rotated between the poles of a magnet.

Section D

Question 18 carries 4 scores. Answer (A) or (B).

  1. (A) A builder uses pulleys to raise loads to the first floor. [4 marks]
    • (a) What is the mechanical advantage of a single fixed pulley? Then why is it used?
    • (b) In a first system of pulleys with 3 movable pulleys, a load of 1600 N is lifted. Find the mechanical advantage and the effort needed (neglect friction and weight of pulleys).
    • (c) To raise the load by 2 m, the rope must be pulled 16 m. Show that there is no gain in work.

    OR

    (B) A 1.5 m long crowbar is used to lift a 2000 N stone. A small stone placed under the bar 30 cm from the end touching the load acts as the fulcrum. Effort is applied at the other end.

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