Question

3) Please circle the correct answers, if there is no correct answer, then leave it blank(do not circle 1. a) red light has a smaller wavelength and lower frequency than blue light. b) red light has a longer wavelength and higher frequency than blue light. 2. Since sound travels at about 340 m/s in air, we can see that a) electromagnetic waves travel at the same speed as sound. b) electromagnetic waves travel slower than sound if air is present. 3. a) as the wavelength of the wave increases, the frequency increases, and the velocity decreases. b) as the wavelength of the wave increases, the frequency increases 4. which of the following is not an electromagnetic wave? a) a sound wave b) a radio wave. 5. a) the difference between the wavelength and frequency of a wave is the velocity of the wave. b) the product of wavelength and frequency of a wave is the velocity of the wave.

Answer 1

The relation between wavelength ($\lambda$) and the frequency ($\nu$) is

                              $\nu = \frac{c}{\lambda}$           (c = 3 x 10⁸ m/s is the speed of light)

i.e.                                                 ..........................(1)

Va

i.e. the wavelength will decrease if the frequency will increase.

The speed of the wave is given by

                                                   ...........................(2)

VA=a

In the visible electromagnetic spectrum, the red light has maximum wavelength. It means that the red light has the lowest frequency.

1. Both statements are incorrect.

2. The electromagnetic waves have a velocity of 3 x 10⁸ m/s. Which is far greater than the speed of sound.

So, both statements are incorrect.

3. According to equation (1) and (2), these two statements are also Incorrect.

4. The radio waves are an electromagnetic wave with frequency in between 3 KHz to 3 GHz. But the sound waves are not an electromagnetic wave, they are longitudinal waves.

5. From equation (2), the first statement (a) is Incorrect but the second (b) statement is Correct.