Leavitt's law is a relationship between

A) a Cepheid variable star's period and luminosity.
B) a galaxy's distance and recession speed.
C) a galaxy's distance and redshift.
D) a main-sequence star's color and luminosity.


A) a Cepheid variable star's period and luminosity.

Physics & Space Science

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A long solenoid (1500 turns/m) carries a current of 20 mA and has an inside diameter of 4.0 cm. A long wire carries a current of 2.0 A along the axis of the solenoid. What is the magnitude of the magnetic field at a point that is inside the solenoid and 1.0 cm from the wire?

a. 78 ?T b. 55 ?T c. 48 ?T d. 68 ?T e. 2.0 ?T

Physics & Space Science

Light is refracted through a diamond. If the angle of incidence is 30°, and the angle of refraction is 12°, what is the index of refraction?

a. 1.3 b. 2.4 c. 2.6 d. 1.8 e. 0.4

Physics & Space Science

Two objects with indices of refraction n1 and n2 are placed in the same liquid substance and have their critical angles measured. If experiment shows that ?c1 > ?c2, then it must also be true that

1. n1 < n2. 2. n1 > n2. 3. n1 = n2. 4.more must be known to determine the relationship between n1 and n2.

Physics & Space Science

Plants are considered part of the ?

What will be an ideal response?

Physics & Space Science