#### 12th Standard Physics English Medium Free Online Test Book Back 1 Mark questions with Answer Key - Part Two

12th Standard

Reg.No. :
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Physics

Time : 00:10:00 Hrs
Total Marks : 10
10 x 1 = 10
1. A parallel plate capacitor stores a charge Q at a voltage V. Suppose the area of the parallel plate capacitor and the distance between the plates are each doubled then which is the quantity that will change?

(a)

Capacitance

(b)

Charge

(c)

Voltage

(d)

Energy density

2. Two short bar magnets have magnetic moments 1.20 Am2 and 1.00 Am2 respectively. They are kept on a horizontal table parallel to each other with their north poles pointing towards the south. They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid-point O of the line joining their centers is (Horizontal components of Earth’s magnetic induction is 3.6 x 10-5 Wb m-2 )

(a)

3.60 × 10-5 Wb m-2

(b)

3.5 × 10-5 Wb m-2

(c)

2.56 × 10-4 Wb m-2

(d)

2.2 × 10-4 Wb m-2

3. An inductor 20 mH, a capacitor 50 μF and a resistor 40 Ω are connected in series across a source of emf v = 10 sin 340 t. The power loss in AC circuit is

(a)

0.76 W

(b)

0.89 W

(c)

0.46 W

(d)

0.67 W

4. Which of the following is an electromagnetic wave?

(a)

α - rays

(b)

β - rays

(c)

$\gamma$ - rays

(d)

all of them

5. A ray of light strikes a glass plate at an angle 60o. If the reflected and refracted rays are perpendicular to each other, the refractive index of the glass is,

(a)

$\sqrt3$

(b)

$\frac{3}{2}$

(c)

$\sqrt{\frac{3}{2}}$

(d)

2

6. The threshold wavelength for a metal surface whose photoelectric work function is 3.313 eV is

(a)

4125 $\mathring { A }$

(b)

3750$\mathring { A }$

(c)

6000$\mathring { A }$

(d)

2062.5$\mathring { A }$

7. Mp denotes the mass of the proton and Mn denotes mass of a neutron. A given nucleus of binding energy B, contains Z protons and N neutrons. The mass M(N,Z) of the nucleus is given by(where c is the speed of light)

(a)

M(N,Z)=NMn+ZMp-Bc2

(b)

M(N,Z)=NMn=ZMp+Bc2

(c)

M(N,Z)=NMn=ZMp-B/c2

(d)

M(N,Z)=NMn=ZMp+B/c2

8. To obtain sustained oscillation in an oscillator,

(a)

Feedback should be positive

(b)

Feedback factor must be unity

(c)

Phase shift must be 0 or 2π

(d)

All the above

9. The variation of frequency of carrier wave with respect to the amplitude of the modulating signal is called _______.

(a)

Amplitude modulation

(b)

Frequency modulation

(c)

Phase modulation

(d)

Pulse width modulation

10. The alloys used for muscle wires in Robots are

(a)

Shape memory alloys

(b)

Gold copper alloys

(c)

Gold silver alloys

(d)

Two dimensional alloys