PYQ Vault

Day 116: CBSE Class 10 Science

5 questions. Try each one first, then open its answer.

  1. Question 1

    Light — Reflection and Refraction. Asked once: 2025 (same type asked 4 times)

    31
    An object is placed at a distance of 20 cm from the optical centre of a concave lens and its image is formed on the same side of the lens as the object. If the distance of the image from optical centre of the lens is 10 cm, use lens formula to determine (i) focal length, and (ii) power of the lens in new Cartesian sign conventions.

  2. Question 2

    Light — Reflection and Refraction. Asked once: 2025 (same type asked 4 times)

    25 (a)
    Out of the two lenses, one concave and the other convex, state which one will diverge a parallel beam of light falling on it. Draw a ray diagram to show the principal focus of the lens.

  3. Question 3

    Light — Reflection and Refraction. Asked once: 2025 (same type asked 4 times)

    24
    The values of absolute refractive indices of kerosene and water are 1.44 and 1.33 respectively. Compare the two media on the basis of their (a) optical density (b) mass density (c) relative speed of propagation of light. What do you infer on the basis of above comparisons ?

  4. Question 4

    Magnetic Effects of Electric Current. Asked once: 2025 (same type asked 4 times)

    36 (A)
    (i) Draw the pattern of the magnetic field lines for the two parallel straight conductors carrying current of same magnitude ‘I’ in opposite directions as shown. Show the direction of magnetic field at a point O which is equidistant from the two conductors. (Consider that the conductors are inserted normal to the plane of a rectangular cardboard.) (ii) In our houses we receive A.C. electric power of 220 V. In electric iron or electric heater cables having three wires with insulation of three different colours – red, black and green are used to draw current from the mains. (a) What are these three different wires called? Name them colourwise. (b) What is the potential difference between the red wire and the black wire? (c) What is the role of the wire with green insulation in case of accidental leakage of electric current to the metallic body of an electrical appliance?

  5. Question 5

    Magnetic Effects of Electric Current. Asked once: 2026 (same type asked 4 times)

    39 (a)
    (i) State the rule which gives the direction of force acting on a current-carrying conductor placed in a magnetic field. (ii) What is a fuse ? Why is it called a safety device ? (iii) Why are electrical appliances with metallic bodies connected to the mains through a three-pin plug, whereas an electric bulb is connected with a two-pin plug ? (iv) What will be the direction of force experienced by the conductor AB due to the magnetic field, when current flows in the direction shown ? Name the law you applied to find the direction.