In a dc motor, induced e.m.f. will be maximum
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(a) When motor takes maximum speed |
(b) When motor starts rotating |
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(c) When speed of motor increases |
(d) When motor is switched off |
(a) When motor takes maximum speed
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The wavelength of sodium light in air is 5890 Å. The velocity of light in air is 3 
The wavelength of light in a glass of refractive index 1.6 would be close to
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(a) 5890 Å |
(b) 3681 Å |
(c) 9424 Å |
(d) 15078 Å |
The de-Broglie wavelength of an electron having 80eV of energy is nearly (1eV = 1.6 × 10–19 J, Mass of electron = 9 × 10–31kg Plank’s constant = 6.6 × 10–34 J-sec)
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(a) 140 Å |
(b) 0.14 Å |
(c) 14 Å |
(d) 1.4 Å |
A person can see clearly only upto a distance of 25 cm. He wants to read a book placed at a distance of 50 cm. What kind of lens does he require for his spectacles and what must be its power
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(a) Concave, – 1.0 D |
(b) Convex, + 1.5 D |
(c) Concave, – 2.0 D |
(d) Convex, + 2.0 D |
Assertion : Torque on the coil is the maximum, when coil is suspended in a radial magnetic field.
Reason : The torque tends to rotate the coil on its own axis.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |