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A student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his textbook. Which of the following statements is correct? (a) The near point of his eyes has receded away (b) The near point of his eyes has come closer to him (c) The far point of his eyes has come closer to him (d) The far point of his eyes has receded away

Answer: (a) The near point of his eyes has receded away Near the point of eye move away for 25 cm in hypermetropia. Hence the person should... View Article

Three incandescent bulbs of 100 W each are connected in series in an electric circuit. In another circuit another set of three bulbs of the same wattage are connected in parallel to the same source. (a) Will the bulb in the two circuits glow with the same brightness? Justify your answer. (b) Now let one bulb in both the circuits get fused. Will the rest of the bulbs continue to glow in each circuit? Give reason.

Answer: A circuit is said to be connected in series when the same amount of current flows through the resistors. In such circuits, the voltage... View Article

B1 , B2 and B3 are three identical bulbs connected as shown in Figure. When all the three bulbs glow, a current of 3A is recorded by the ammeter A. i) What happens to the glow of the other two bulbs when the bulb B1 gets fused? ii) What happens to the reading of A1 , A2 , A3 and A when the bulb B2 gets fused? iii) How much power is dissipated in the circuit when all the three bulbs glow together?

Answer: (i) When B1 is fused, there will be no influence on the glow of the other two bulbs, which will remain the same since bulb glowing is... View Article

A current of 1 ampere flows in a series circuit containing an electric lamp and a conductor of 5 Ω when connected to a 10 V battery. Calculate the resistance of the electric lamp. Now if a resistance of 10 Ω is connected in parallel with this series combination, what change (if any) in current flowing through 5 Ω conductor and potential difference across the lamp will take place? Give reason.

Answer: (1) Let R1 be the resistance of the electric lamp. R2 be the resistance of the conductor. In series total resistance = R1 + R2 = 5 +... View Article