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# IIT Physics Question

Q1. An α-particle of energy 5 MeV is scattered through 180° by a fixed uranium nucleus. The distance of closest approach is of the order of
(a) 10–12 cm
(b) 10–10 cm
(c) 1A
(d) 10–15 cm

Q2. A circular loop of radius 0.3 cm lies parallel to a much bigger circular loop of radius 20 cm. The centre of the small loop is on the axis of the bigger loop. The distance between their centres is 15 cm. If a current of 2.0 A flows through the smaller loop, then the flux linked with bigger loop is
(a) 9.1 × 10–11 weber
(b) 6 × 10–11 weber
(c) 3.3 × 10–11 weber
(d) 6.6 × 10–9 weber

Q3. A charged oil drop is suspended in a uniform field of 3 × 104 v/m so that it neither falls nor rises. The charge on the drop will be (Take the mass of the charge = 9.9 × 10–15 kg and g = 10 m/s2)
(a) 1.6 × 10–18 C
(b) 3.2 × 10–18 C
(c) 3.3 × 10–18 C
(d) 4.8 × 10–18 C

Q4. Two points P and Q are maintained at the potentials of 10 V and – 4 V, respectively. The work done in moving 100 electrons from P to Q is:
(a) 9.60 × 10–17 J
(b) -2.24 × 10–16 J
(c) 2.24 × 10–16 J
(d) –9.60 × 10–17 J

Q5. A particle of mass 10 g is kept on the surface of a uniform sphere of mass 100 kg and radius 10 cm. Find the work to be done against the gravitational force between them to take the particle far away from the sphere (you may take G = 6.67× 10 –11 Nm2/kg2)
(a) 3.33 × 10 –10 J
(b) 13.34 × 10 –10 J
(c) 6.67 × 10 –10 J
(d) 6.67 × 10 –9 J

Q6. Capacitance (in F) of a spherical conductor with radius 1 m is
(a) 1.1 × 10–10
(b) 10–6
(c) 9 × 10–9
(d) 10–3

Q7. The potential at a point x (measured in μ m) due to some charges situated on the x-axis is given by V(x) = 20/(x2 – 4) volt
The electric field E at x = 4 μ m is given by
(a) (10/9) volt/ μ m and in the +ve x direction
(b) (5/3) volt/ μ m and in the –ve x direction
(c) (5/3) volt/ μ m and in the +ve x direction
(d) (10/9) volt/ μ m and in the –ve x direction

Q8. An electric current is passed through a circuit containing two wires of the same material, connected in parallel. If the lengths and radii are in the ratio of 4/3 and 2/3, then the ratio of the current passing through the wires will be
(a) 8/9
(b) 1/3
(c) 3
(d) 2

Q9. For a transistor amplifier in common emitter configuration for load impedance of 1kΩ (hfe = 50 and hoe = 25) the current gain is
(a) – 24.8
(b) – 15.7
(c) – 5.2
(d) – 48.78

Q10. If the ratio of the concentration of electrons to that of holes in a semiconductor is 7/5 and the ratio of currents is 7/4, then what is the ratio of their drift velocities?
(a) 5/8
(b) 4/5
(c) 5/4
(d) 4/7
1. a 2. a 3. c 4. c 5. c 6. a 7. a 8. b 9. d 10. c

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