INDUS CENTRE OF ACADEMIC LEARNING, D.G.KHAN.PAPER: PHYSICS CLASS: XI CH:7 TEST 14 MARKS:30 TIME: 1 H, 20 MINUTES1. The waves produce in microwave oven has the wavelength

a. 12 cm b. 200 cm c. 12000 cm d. zero

2. The waves produce in microwave oven has the freq

a. 2450 MHz b. 2450 Hzc. 2450 KHz d. 2450 KHz

3. In damping the decrease in amplitude caused by

a. oscillations b. freq

c. time period d. dissipated forces

4. Forced oscillations are mostly occur in

a. electric circuits b. loud music c. machinery d. all

5. If we draw a graph between frequency and amplitude of a vibrating system for heavy damping at resonating freq. the curve will be

a. sharp

b. flat

c. fairly flat d. sharp slightly

6.At what place motion of simple pendulum will be slowest.

a. poles b. equator c. on the surface of earth d. at the center of earth

7. The time period of a simple pendulum is doubled, when:

(a) its length is doubled (b) mass of bob is doubled

8.The length of second pendulum is.

(a) 100 cm(b) 99 cm (c) 99.2 cm (d) 98 cm

9. The force responsible for the vibratory motion of the simple pendulum.

(a) mgcos (b) mg sin (c) mg tan (d) mg

Short questions.Note attempt any 5

marks 5x2=10

1. What is difference between free and forced oscillations.

2. Define damped oscillations

3. Can we realize an ideal simple pendulum?

4. Does frequency depends on amplitude for harmonic oscillators?

5.Explain the relation between total energy, potential energy and kinetic energy for a body oscillating with SHM.

6.Describe some common phenomenon in which resonance plays an important role

Long question

marks:5+3+3

a.Define and explain resonance.

b.A simple pendulum is 50.0 cm long. What will be its frequency of vibration at a

place where g = 9.8 ms2?

c. A 100.0 g body hung on a spring elongates the spring by 4.0 cm. when a

certain object is hung on the spring and set vibrating, its period is 0.568 s. what

is the mass of the object pulling the spring?.