A 1,760 W toaster, a 1,420 W electric frying pan, and an 85 W lamp are plugged into the same outlet in a 15 A, 120 V circuit. (The three devices are in parallel when plugged into the same socket.) (a) What current (in A) is drawn by each device

Toaster = I = 14.67 A

Frying Pan = 11.83 A

Lamp = 0.71 A

Explanation:

The electric power is given as:

where,

I = current

P = Power

V = Voltage = 120 V

FOR TOASTER:

P = 1760 W

Therefore,

I = 14.67 A

FOR FRYING PAN:

P = 1420 W

Therefore,

I = 11.83 A

FOR LAMP:

P = 85 W

Therefore,

I = 0.71 A

a. as a moving sound source approaches a stationary observer, the frequency of the sound increases, therefore the wavelength is shorter

Explanation:

This effect is known as Doppler effect. When a moving sound source approaches a stationary observer, the wavefronts of the wave appear to be closer to each other: as a result, the frequency of the sound wave appears to be increased. The wavelength of the sound is inversely proportional to the frequency:

where v is the speed of the wave and f the frequency: therefore, as the frequency increases, the wavelength gets shorter.

b. As the sound source moves away from the observer, the pitch of the sound decreases and the wavelength increases

Explanation:

When the sound source moves away from the observer, the effect is opposite: the wavefronts appear to spread apart from each other, so the frequency of the sound appears to decreases, and as a result, the wavelength increases.

The pitch of a sound is related to how we perceive the sound, and it is directly proportional to the frequency: therefore, since the frequency decreases, the pitch decreases as well.