Model Paper 3 — Physics STD 12 Science — Question

A. Current flow inside the capacitor due to accumulation of charges on the capacitor walls is called displacement current.
B. Current due to the flow of electrons due to some potential difference is called as conduction current. 
C. Displacement current came into existence when Maxwell observed that if a magnetic compass is placed between the capacitors the needle gets deflected which signifies presence of magnetic fields which would possibly caused due to some changing current.
D. Displacement current change the actual motion of electric charges.
Which of the above statement(s) is/ are correct?

The charge on 500 cc  of water due to protons will be

(a) 6.0

(b) 2.67

(c) 6

(d) 1.67

Let p and E denote the linear momentum and energy of a photon. If the wavelength is decreased:

1. Both p and E increase.
2. P increases and E decreases.
3. P decreases and E increases.
4. Both p and E decrease.

The sun makes 0.5^o angle on earth surface.  Its image is made by convex lens of 50 cm focal length.  The diameter of the image will be     

(a) 5 mm

(b) 4.36 mm

(c) 7 mm

(d) None of these

Which of the following statements is false?

When a resistance of 2 ohm is connected across the terminals of a cell, the current is 0.5 A. When the resistance is increased to 5 ohm, the current is 0.25 A. The e.m.f. of the cell is

(a) 1.0 V

(b) 1.5 V

(c) 2.0 V

(d) 2.5 V

Assertion   :   In photoemissive cell inert gas is used.

Reason       : Inert gas in the photoemissive cell gives greater current.

(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.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

A rectangular loop is being pulled at a constant speed v, through a region of certain thickness d, in which a uniform magnetic field B is set up. The graph between position x of the right hand edge of the loop and the induced emf E will be

(a)

(b)

(c)

(d)

X-ray from a Coolidge tube is incident on a thin aluminium foil. The intensity of the X-ray transmitted by the foil is found to be I₀. The heating current is increased to increase the temperature of the filament. The intensity of the X-ray transmitted by the foil will be:

1. zero
2. < I₀
3. I₀
4. > I₀

Each plate of a parallel plate capacitor has a charge q on it. The capacitor is now connected to a batter. Now:

1. The facing surfaces of the capacitor have equal and opposite charges.
2. The two plates of the capacitor have equal and opposite charges.
3. The battery supplies equal and opposite charges to the two plates.
4. The outer surfaces of the plates have equal charges.