Where did the cosmic microwave background (CMB) come from?

a. photons emitted from the first stars
b. photons released from hydrogen in our galaxy
c. light scattered by dust in our Solar System
d. photons released when electrons and nuclei combined for the first time


d

Physics & Space Science

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Series/Parallel Circuits: For the circuit shown in the figure, what is the power dissipated in the 2.0-? resistor? All the numbers shown are accurate to three significant figures.

A. 5.33 W B. 8.00 W C. 6.67 W D. 2.67 W E. 3.56 W

Physics & Space Science

Total Internal Reflection: Light travels from crown glass, with a refractive index of 1.52, into water, having a refractive index of 1.33? The critical angle for this interface is closest to which one of the following angles?

A. 42° B. 48° C. 53° D. 57° E. 61°

Physics & Space Science

The source of energy that powers the Sun is

A) chemical potential energy of hydrogen. B) mass energy released by nuclear fusion. C) gravitational potential energy of the contraction of the gas cloud that formed the Sun. D) kinetic energy of the orbital motion of the Sun. E) thermal energy of the hydrogen atoms in the Sun.

Physics & Space Science

Based on current scientific evidence, what is the likelihood that life on Earth formed spontaneously from increasingly complex chemical reactions?

A) very likely B) certain C) impossible D) very unlikely

Physics & Space Science