#### Electromagnetic Waves One Mark Questions

12th Standard EM

Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 10
5 x 1 = 5
1. Consider an oscillator which has a charged particle and oscillates about its mean position with a frequency of 300 MHz. Th e wavelength of electromagnetic waves produced by this oscillator is

(a)

1 m

(b)

10 m

(c)

100 m

(d)

1000 m

2. Th e electric and the magnetic field, associated with an electromagnetic wave, propagating along X axis can be represented by

(a)

$\vec { E } ={ E }_{ 0 }\hat { j }$ and $\vec { B } ={ B }_{ 0 }\hat { k }$

(b)

$\vec { E } ={ E }_{ 0 }\hat { k }$ and $\vec { B } ={ B }_{ 0 }\hat { j }$

(c)

$\vec { E } ={ E }_{ 0 }\hat { i }$ and $\vec { B } ={ B }_{ 0 }\hat { j }$

(d)

$\vec { E } ={ E }_{ 0 }\hat { j }$ and $\vec { B } ={ B }_{ 0 }\hat { i }$

3. In an electromagnetic wave in free space the rms value of the electric fi eld is 3 V m−1. The peak value of the magnetic field is

(a)

1.414 × 10-8 T

(b)

1.0 × 10-8 T

(c)

2.828 × 10-8 T

(d)

2.0 × 10-8 T

4. Electromagnetic waves are produced by

(a)

static charge

(b)

moving charge

(c)

an accelerating charge

(d)

chargeless particles

5. Which of the following electromagnetic waves has the highest frequency?

(a)

(b)

micro waves

(c)

X- rays

(d)

૪-rays

6. 5 x 1 = 5

8. (1)

Spectrum of Carbon Arc

9. Continuous Emission spectra

10. (2)

Spectra of H2 gas

11. Band Emission spectraSpectra of H, gas

12. (3)

Incandescent solids

13. Line Absorption spectra

14. (4)

Solar spectrum

15. Fraunhofer Lines

16. (5)

6x10-10m to 4x10-7m