- A3.7 × 1010 Disintegration/ sec.
- B3.2 × 108 Disintegration/ sec.
- C2.8 × 1010 Disintegration/ sec.
- DNone of these.
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Assertion : If three identical bulbs are connected in series as shown in figure then on closing the switches. Bulb C short circuited and hence illumination of bulbs A and B decreases.

Reason : Voltage on A and B decreases
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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. |
An electric heater of resistance 6 ohm is run for 10 minutes on a 120 volt line. The energy liberated in this period of time is
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(a) 7.2 |
(b) 14.4 |
(c) 43.2 |
(d) 28.8 |
Current provided by a battery is maximum when
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(a) Internal resistance equal to external resistance |
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(b) Internal resistance is greater than external resistance |
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(c) Internal resistance is less than external resistance |
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(d) None of these |
Dual nature of radiation is shown by
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(a) Diffraction and reflection |
(b) Refraction and diffraction |
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(c) Photoelectric effect alone |
(d) Photoelectric effect and diffraction |
Assertion : Charge is quantized
Reason : Charge, which is less than 1 C is not possible
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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. |
The slope of plate characteristic of a vacuum tube diode for certain operating point on the curve is The plate resistance of the diode and its nature respectively
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(a) 100 kilo-ohms static |
(b) 1000 kilo-ohms static |
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(c) 1000 kilo-ohms dynamic |
(d) 100 kilo-ohms dynamic |
A convex mirror has a focal length f. A real object is placed at a distance f in front of it from the pole produces an image at
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(a) Infinity |
(b) f |
(c) f/2 |
(d) 2f |