Explanation:
Force on charged particle in an electric eld, $\text{F} = \text{qE} \ ...(1)$
Force on charged particle in a magnetic eld $\text{F} = \text{q} (\text{v}\times\text{b}) = \text{qvB} \sin\theta \ ...(2) $
Where boldface letter represent vector nature of that quantity, q is charge of the particle, v is the velocity of the particle( if any), and $\theta$ is the angle between velocity and magnetic eld.
From (1), FE = 0 only when either q = 0 or E = 0.
Let q ≠ 0, and F ≠ 0, then we must have E ≠ 0
From (2), if q ≠ 0, v ≠ 0 and B ≠ 0 even then FB can be 'zero' because of θ = 0° or 180°
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For a nucleus to be stable, the correct relation between neutron number N and Proton number Z is
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(a) N > Z |
(b) N = Z |
(c) N < Z |
(d) N ≥ Z |
The resistivity of a wire depends on its
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(a) Length |
(b) Area of cross-section |
(c) Shape |
(d) Material |
An object is placed at a distance of f/2 from a convex lens. The image will be
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(a) At one of the foci, virtual and double its size |
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(b) At 3f / 2, real and inverted |
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(c) At 2f, virtual and erect |
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(d) None of these |
Assertion : A P-N photodiode is made from a semiconductor for which Eg = 2.8 eV. This photo diode will not detect the wavelength of 6000 nm.
Reason : A PN photodiode detect wavelength l if 
.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(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. |
|
(d) If the assertion and reason both are false. |
With the increase in principle quantum number, the energy difference between the two successive energy levels
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(a) Increases |
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(b) Decreases |
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(c) Remains constant |
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(d) Sometimes increases and sometimes decreases |
How many NAND gates are used to form an AND gate
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(a) 1 |
(b) 2 |
(c) 3 |
(d) 4 |