Alexis is studying how lenses work. She looks through a magnifying glass and through the peephole of a door.
Which best describes a difference between the lenses used in these 2 devices?

A. The lens in the magnifying glass can produce both real and virtual images, but the lens in the peephole can produce only real images.

B. The lens in the magnifying glass can produce only real images, but the lens in the peephole can produce both real and virtual images.

C. The lens in a magnifying glass can produce both upright and inverted images, but the lens in the peephole can produce only upright images.

D. The lens in a magnifying glass can produce only inverted images, but the lens in a peephole can produce inverted and upright images.

gets less

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2