A charged ball B hangs from a silk thread S, which makes an angle θ with a large charged conducting sheet P, as shown in the figure. The surface charge density σ of the sheet is proportional to
|
(a) sin θ |
(b) tan θ |
(c) cos θ |
(c) cos θ |
(b) tan θ
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A small bar magnet has a magnetic moment 1.2 A-m2. The magnetic field at a distance 0.1 m on its axis will be : (m0 = 4p × 10–7 T-m/A)
|
(a) 1.2 × 10–4 T |
(b) 2.4 × 10–4 T |
(c) 2.4 × 104 T | (d) 1.2 × 104 T |
A point object O is placed on the principal axis of a convex lens of focal length f = 20cm at a distance of 40cm to the left of it. The diameter of the lens is 10cm. An eye is placed 60cm to right of the lens and a distance h below the principal axis. The maximum value of h to see the image is:
A potential difference of 2V is applied between the opposite faces of a Ge crystal plate of area 1 cm2 and thickness 0.5 mm. If the concentration of electrons in Ge is 2 × 1019/m3 and mobilities of electrons and holes are 0.36 
and 0.14 respectively, then the current flowing through the plate will be
|
(a) 0.25 A |
(b) 0.45 A |
(c) 0.56 A |
(d) 0.64 A |
The length of the wire is doubled. Its conductance will be
|
(a) Unchanged |
(b) Halved |
|
(c) Quadrupled |
(d) 1/4 of the original value |
In Young’s double slit experiment, the intensity of light coming from the first slit is double the intensity from the second slit. The ratio of the maximum intensity to the minimum intensity on the interference fringe pattern observed is
|
(a) 34 |
(b) 40 |
(c) 25 |
(d) 38 |