- AOf the same order as the wavelength of light
- BMuch smaller than the wavelength of light
- CMuch larger than the wavelength of light
- DOf the order of 1mm
Explanation:
Ray optics is valid when characteristics dimensions are larger than the wavelength of the light, so that rectilinear property of light can be used.
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A 25 W, 220 V bulb and a 100 W, 220 V bulb are connected in parallel across a 440 V line
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(a) Only 100 watt bulb will fuse |
(b) Only 25 watt bulb will fuse |
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(c) Both bulbs will fuse |
(d) None of the bulbs will fuse |
In a PN-junction diode
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(a) The current in the reverse biased condition is generally very small |
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(b) The current in the reverse biased condition is small but the forward biased current is independent of the bias voltage |
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(c) The reverse biased current is strongly dependent on the applied bias voltage |
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(d) The forward biased current is very small in comparison to reverse biased current |
Assertion : Electric lines of force cross each other.
Reason : Electric field at a point superimpose to give one resultant electric field.
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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 assertion is false but reason is true. |
In a common emitter transistor, the current gain is 80. What is the change in collector current, when the change in base current is 250 mA
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(a) 80 × 250 mA |
(b) (250 – 80) mA |
(c) (250 + 80) mA |
(d) 250/80 mA |