Chapter 19 - Dawn of ModernMhysics - 3

Chapter 19 - Dawn of ModernMhysics - 3

1. The speed of light in free space is:

a) 3x107m/s
b) 3x109m/s
c) 3x108m/s
d) 3x1010m/s

2. Due to the relative motion of observer and frame of reference time:

a) Dilates
b) Contracts
c) Constant
d) uniform

3. Earth’s orbital speed is:

a) 45 km/s
b) 70 km/s
c) 60 km/s
d) 30 km/s

4. Black bodies are formed of:

a) Reflecting solid objects
b) Non reflecting solid objects
c) Non metals
d) Metals

5. The antiparticle of electron is:

a) Proton
b) Positron
c) Neutron
d) Meson

6. As a result of annihilation of electron and positron, number of γ –ray photons are:

a) Two
b) Three
c) Four
d) One

7. The energy of photon of radio waves is about:

a) 10-6ev
b) 10-12ev
c) 10-10ev
d) 10-8ev

8. Identify where the photocell can be effectively used:

a) As a counting element
b) As a burglar alarm
c) All
d) For opening doors automatically

9. A photon is always considered to be:

a) Moving with speed of light
b) At rest
c) Moving with speed of sound
d) In accelerated form

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