16. Two stages of experiment conducted with a solenoid and a magnet is given below :
Magnets shown in Fig-A and Fig-B are stationary magnet and a moving magnet respectively)
(a) In which stage, the galvanometer deflects ?
(b) Explain the reason for this deflection in galvanometer with the help of scientific principle that you have learned.
(c) Write any two devices that works on this principle.
Answer
a) Figure B
b) Electromagnetic induction
c) Moving coil Microphone, Generator
17. Explain the scientific reason behind the phenomena given below.
(a The path of sunlight is visible in a misty morning.
(b) Newton's colour disc appears white when rotated fast,
(c) The rising and setting sun appears red.
(d) A person can see the far object and near object clearly.
Answer
a. Tyndall Effect.
b. Persistence of vision
c. Scattering of light.
d. Power of accommodation Ω
18. Analyse the circuits P and Q.
(a) In which circuit, the resistors get the same voltage ?
(b) Calculate the voltage across the resistor K2 in the circuit (P).
(c) If current due to the applied emf is flowing through these two circuits for a time of 5 minutes, which circuit will produce more heat energy ? Explain.
Answer
a)
Q - 10V
P - 5V
b) 5 V
c)
Q will be producing more Heat.
Effective resistance of P = 100 + 100 = 200 Ω
$$Effective Resistance, Q = \frac{100}{2} = 50 Ω$$
$$H = \frac{V^{2}t}{R}$$
There when resistance decreases , heat increases
19. Observe the figure and answer the following questions. B1 and B2 are identical bulbs.
(a) Which bulb will glow in the circuits 1
(b) If the battery in the circuit is replaced by an ac source of the same voltage, what change can be observed in the working of the bulbs? Explain the reasons for the change.
Answer
a) B1
b) Two bulbs B1, B2 glow due to mutual Induction Intensity of B1 decreases due to self induction
20. Define the following terms of a lens.
(a) Optic center.
(b) Center of curvature.
(c) Principal focus of convex lens.
(d) Focal length of concave lens.
Answer
a. Optic center is the mid point of a lens.
b. Center of curvature is the center of the imaginary spheres of which the sides of the lens are parts.
c. Light rays incident parallel and close to the principal axis after refraction converges to a point on the principal axis of a convex lens. This point is called principal focus of convex lens.
d. Focal length of convex lens is the distance from the optic centre to the principal focus.
Magnets shown in Fig-A and Fig-B are stationary magnet and a moving magnet respectively)
(b) Explain the reason for this deflection in galvanometer with the help of scientific principle that you have learned.
(c) Write any two devices that works on this principle.
Answer
a) Figure B
b) Electromagnetic induction
c) Moving coil Microphone, Generator
17. Explain the scientific reason behind the phenomena given below.
(a The path of sunlight is visible in a misty morning.
(b) Newton's colour disc appears white when rotated fast,
(c) The rising and setting sun appears red.
(d) A person can see the far object and near object clearly.
Answer
a. Tyndall Effect.
b. Persistence of vision
c. Scattering of light.
d. Power of accommodation Ω
18. Analyse the circuits P and Q.
(b) Calculate the voltage across the resistor K2 in the circuit (P).
(c) If current due to the applied emf is flowing through these two circuits for a time of 5 minutes, which circuit will produce more heat energy ? Explain.
Answer
a)
Q - 10V
P - 5V
b) 5 V
c)
Q will be producing more Heat.
Effective resistance of P = 100 + 100 = 200 Ω
$$Effective Resistance, Q = \frac{100}{2} = 50 Ω$$
$$H = \frac{V^{2}t}{R}$$
There when resistance decreases , heat increases
19. Observe the figure and answer the following questions. B1 and B2 are identical bulbs.
(a) Which bulb will glow in the circuits 1
(b) If the battery in the circuit is replaced by an ac source of the same voltage, what change can be observed in the working of the bulbs? Explain the reasons for the change.
Answer
a) B1
b) Two bulbs B1, B2 glow due to mutual Induction Intensity of B1 decreases due to self induction
20. Define the following terms of a lens.
(a) Optic center.
(b) Center of curvature.
(c) Principal focus of convex lens.
(d) Focal length of concave lens.
Answer
a. Optic center is the mid point of a lens.
b. Center of curvature is the center of the imaginary spheres of which the sides of the lens are parts.
c. Light rays incident parallel and close to the principal axis after refraction converges to a point on the principal axis of a convex lens. This point is called principal focus of convex lens.
d. Focal length of convex lens is the distance from the optic centre to the principal focus.
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