Electromagnetic Waves — Physics STD 12 Science — Question

A plane wavefront (λ = 6   falls on a slit 0.4 mm  wide. A convex lens of focal length 0.8 m  placed behind the slit focusses the light on a screen. What is the linear diameter of second maximum

(a) 6mm

(b) 12 mm

(c) 3 mm

(d) 9 mm

If the two ends of a p-n junction are joined by a wire:

The minimum distance between an object and its real image formed by a convex lens of focal length f is:

A coil has an area of 0.05 m² and it has 800 turns. It is placed perpendicularly in a magnetic field of strength 4 ,  it is rotated through 90°  in 0.1 sec. The average e.m.f. induced in the coil is

(a) 0.056 V

(b) 0.046 V

(c) 0.026 V

(d) 0.016 V

‘X’ is a substance which does not allow the flow of charges through it but permits them to exert electrostatic forces on one another through it. Identify X.

Which of the following is not the function of a NOT gate?

A charged water drop whose radius is 0.1 μm  is in equilibrium in an electric field. If charge on it is equal to charge of an electron, then intensity of electric field will be (g = 10

(a) 1.61 N/C

(b) 26.2 N/C

(c) 262 N/C

(d) 1610 N/C

A 25 watt, 220 volt bulb and a 100 watt, 220 volt bulb are connected in parallel across a 220 volt line. Which bulb will glow more brightly

(a) 25 watt bulb	(b) 100 watt bulb
(c) Both will have same brightness	(d) First 25 watt then 100 watt

A bar magnet having centre O has a length of 4 cm. Point P₁ is in the broad side-on and P₂ is in the end side-on position with OP₁ = OP₂ = 10 metres. The ratio of magnetic intensities H at P₁ and P₂ is

(a)	(b)
(c)	(d)

A stream of electrons is projected horizontally to the right. A straight conductor carrying a current is supported parallel to the electron stream and above it. If the current in the conductor is from left to right, what will be the effect on the electron stream?