Three identical capacitors are combined differently. For the same voltage to each combination, the one that stores the greatest energy is
|
(a) Two in parallel and the third in series with it |
(b) Three in series |
|
(c) Three in parallel |
(d) Two in series and third in parallel with it |
(c) Three in parallel
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The charge given to a hollow sphere of radius 10 cm is 3.2 × 10–19 coulomb. At a distance of 4 cm from its centre, the electric potential will be
|
(a) 28.8 × |
(b) 288 volts |
(c) 2.88 volts |
(d) Zero |
A cube of a metal is given a positive charge Q. For the above system, which of the following statements is true
|
(a) Electric potential at the surface of the cube is zero |
|
(b) Electric potential within the cube is zero |
|
(c) Electric field is normal to the surface of the cube |
|
(d) Electric field varies within the cube |
Two bulbs are working in parallel order. Bulb A is brighter than bulb B. If 
and 
are their resistance respectively then
|
(a) |
(b) |
(c) |
(d) None of these |
For a triode m = 64 and gm =1600 m mho. It is used as an amplifier and an input signal of 1V (rms) is applied. The signal power in the load of 40 kW will be
|
(a) 23.5 mW |
(b) 48.7 mW |
(c) 25.6 mW |
(d) None of these |
Chromatic aberration of lens can be corrected by
|
(a) Reducing its aperature |
|
(b) Proper polishing of its two surfaces |
|
(c) Suitably combining it with another lens |
|
(d) Providing different suitable curvature to its two surfaces |
In a moving coil galvanometer, the deflection of the coil θ is related to the electrical current i by the relation
|
(a) i ∝ tanθ |
(b) i ∝ θ |
(c) i ∝ |
(d) i ∝ |
An object of length 6 cm is placed on the principle axis of a concave mirror of focal length f at a distance of 4f. The length of the image will be
|
(a) 2 cm |
(b) 12 cm |
(c) 4 cm |
(d) 1.2 cm |
