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The wavelength of most energetic X-rays emitted when a metal target is bombarded by 40KeV electrons, is approximately (h = 6.63 
)
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(a) 300 Å |
(b) 10 Å |
(c) 4 Å |
(d) 0.31 Å |
A presbyopic patient has near point as 30 cm and far point as 40 cm. The dioptric power for the corrective lens for seeing distant objects is
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(a) 40 D |
(b) 4 D |
(c) – 2.5 D |
(d) 0.25 D |
Assertion : The positively charged nucleus of an atom has a radius of almost 
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Reason : In a-particle scattering experiment, the distance of closest approach for a-particles is 
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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. |
$\omega\propto\frac{1}{\text{r}}$
$\omega\propto\text{r}$
$\omega=0$
$\omega$ is independent of r.
The correct curve between the magnetic induction (B) along the axis of a long solenoid due to current flow i in it and distance x from one end is
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(a)
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(b)
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(c)
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(d)
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In a diode valve, the state of saturation can be obtained easily by
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(a) High plate voltage and high filament current |
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(b) Low filament current and high plate voltage |
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(c) Low plate voltage and high cathode temperature |
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(d) High filament current and high plate voltage |
Which impurity is doped in Si to form N-type semi-conductor?
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(a) Al |
(b) B |
(c) As |
(d) None of these |
An electron is accelerated through a potential difference of 1000 volts. Its velocity is nearly
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(a) 3.8 |
(b) 1.9 |
(c) 1.9 |
(d) 5.7 |
