Question

1.a)

A diffraction pattern is produced on a viewing screen by using a single slit with blue light. Which of the following is true? 1)Using red light will broaden the pattern; widening the slit will also broaden the pattern. 2)Using red light will narrow the pattern; widening the slit will broaden the pattern. 3)Using red light will broaden the pattern; widening the slit will narrow the pattern. 4)Using red light will narrow the pattern; widening the slit will also narrow the pattern.

1.b

Which of the following statements about sound intensities measured in dB (decibels) is correct?

Sounds with decibel levels less than zero cannot exist.

Mathematically, our intensity formula can never give us negative decibels.

Most people can perceive sounds that have negative debibel levels.

Sounds with negative decibel levels are not generally perceptible to humans.

1.c)

A diffraction pattern is produced on a viewing screen by using a single slit with blue light. Which of the following is true?

	Using red light will broaden the pattern; widening the slit will also broaden the pattern.
	Using red light will narrow the pattern; widening the slit will broaden the pattern.
	Using red light will broaden the pattern; widening the slit will narrow the pattern.
	Using red light will narrow the pattern; widening the slit will also narrow the pattern.

Answer 1

1a) 3)Using red light will broaden the pattern; widening the slit will narrow the pattern.

because, width of a band, beta = lamda*R/d

lamda is the wavelength and d is the size of slit.

lamda(red) > lamda(blue)

1b) Sounds with negative decibel levels are not generally perceptible to humans.

the imnimum sound intensity, Io = 10^-12 W/m^2

which corrresponds to 0 dB sound.

so, if the sound intensity is less than 10^-12 W/m^2, our ear can not hear the sound.

1c) Using red light will broaden the pattern; widening the slit will narrow the pattern.