Physics - Questions (Section-1)
49Light Emitting Diodes (LED) is used in fancy electronic devices such as toys emit
A. X-raysB. ultraviolet light
C. visible light D. radio waves
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50Light from the star, Alpha Centauri, which is nearest to the earth after the sun, reaches the earth in
A. 4.2 secondsB. 42 seconds
C. 4.2 years D. 42 years
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51Mercury is commonly used as a thermometric fluid rather than water because
A. specific heat of mercury is less than waterB. specific heat of mercury is more than water
C. mercury has greater visibility than water D. density of mercury is more than the water
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52Optical fibre works on the
A. principle of refractionB. total internal reflection
C. scattering D. interference
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53Out of the following pairs, which one does not have identical dimension?
A. Moment of inertia and moment of a forceB. Work and Torque
C. Angular momentum and Planck's constant D. Impulse and Momentum
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54Radio telescopes are better than optical telescopes because
A. they can detect faint galaxies which no optical telescope canB. they can work even in cloudy conditions
C. they can work during the day and night D. All of the above
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