Current Electricity — Physics STD 12 Science — Question

Equal charges q are placed at the vertices A and B of an equilateral triangle ABC of side a. The magnitude of electric field at the point C  is

(a)

(b)

(c)

(d)

An object is placed at a distance u from a simple microscope of focal length f. The angular magnification obtained depends:

1. On f but not on u.
2. On u but not on f.
3. On f as well as u.
4. Neither on f nor on u.

Conditions of diffraction is

(a)

(b)

(c)

(d) None of these

A 3volt battery with negligible internal resistance is connected in a circuit as shown in the figure.  The current I, in the circuit will be

(a) 1/3 A

(b) 1 A

(c) 1.5 A

(d) 2 A

Which of the following systems may be adequately described by classical physics?

If  and  be the size of the images respectively for the two positions of lens in the displacement method, then the size of the object is given by

(a)

(b)

(c)

(d)

A rectangular block of glass ABCD has a refractive index 1.6. A pin is placed midway on the face AB (Fig). When observed from the face AD, the pin shall:

When a piece of aluminium wire of finite length is drawn through a series of dies to reduce its diameter to half its original value, its resistance will become

(a) Two times

(b) Four times

(c) Eight times

(d) Sixteen times

An electron and proton have the same de-Broglie wavelength. Then the kinetic energy of the electron is

(a) Zero

(b) Infinity

(c) Equal to the kinetic energy of the proton

(d) Greater than the kinetic energy of the proton