Physics Model Question Paper 2: (For Class 11 and 12 and Pre-Medical/Engineering Entrance)

1.

B₁, B₂ and B₃ are the three identical bulbs connected to a battery of steady e.m.f. with key K closed. What happens to the brightness of the bulbs B₁ and B₂ when the key is opened?

(A) Brightness of the bulb, B₁ decreases and that of B₂ increases.

(B) Brightness of the bulbs B₁ and B₂ decreases.

(C) Brightness of the bulbs B₁ increases and that of B₂ decreases.

(D) Brightness of the bulbs B₁ and B₂ increases.

Answer: (A)

2.

Current 'I' is flowing in a conductor shaped as shown in the figure. The radius of the curved part is r and the length of straight portion is very large. The value of the magnetic field at the centre O will be

(A)

(B)

(C)

(D)

Answer: (A)

3.

Figure shows a mixture of blue, green and red colored rays incident normally on a right angled prism. The critical angles of the material of the prism for red, green and blue are 46°, 44° and 43° respectively. The arrangement will separate

(A) red colour from blue and green

(B) blue colour from red and green

(C) green colour from red and blue

(D) all the three colours.

Answer: (A)

4.

Identify the logic operation performed by the circuit given here.

(A) NOT

(B) NAND

(C) OR

(D) NOR

Answer: (C)

5.

In the circuit given here, the points A, B and C are 70 V, zero, 10 V respectively. Then

(A) currents in the paths AD, DB and DC are in the ratio of 1 : 2 : 3.

(B) currents in the paths AB, DB and DC are in the ratio of 3 : 2: 1.

(C) the point D will be at a potential of 60 V.

(D) the point D will be at a potential of 20 V.

G

6.

PQ and RS are long parallel conductors separated by certain distance. M is the midpoint between them (see the figure). The net magnetic field at M is B. Now, the current 2A is switched off. The field at M now becomes ______.

(A)

(B) 3B

(C) 2B

(D) 3

Answer: (D)

7.

The coefficient of thermal conductivity of copper is 9 times that of steel. In the composite cylindrical bar shown in the figure, what will be the temperature at the junction of copper and steel?

(A) 75°C

(B) 67°C

(C) 25°C

(D) 33°C

Answer: (A)

8.

The equivalent resistance between the points A and B will be (each resistance is 15 W)

(A) 30 W

(B) 8 W

(C) 10 W

(D) 40 W

Answer: (B)

9.

The moment of inertia of a circular disc of radius 2 m and mass 1 kg about an axis passing through the centre of mass but perpendicular to the plane of the disc is 2 kgm². Its moment of inertia about an axis parallel to this axis but passing through the edge of the disc is ______ (See the given figure).

(A) 10 kgm²

(B) 6 kgm²

(C) 8 kgm²

(D) 4 kg m²

Answer: (B)

10.

The resultant force on the current loop PQRS due to a long current carrying conductor will be

(A) 10^-4 N

(B) 3.6 ´ 10^-4 N

(C) 1.8 ´ 10^-4 N

(D) 5 ´ 10^-4 N

Answer: (D)