If barium has a work function of 2.6 eV, what is its cutoff wavelength when used as a phototube target? (h = 6.63 × 10^?34 J?s, c = 3.00 × 10^8 m/s, 1 eV = 1.60 × 10^?19 J and 1 nm = 10?9 m)
a. 765 nm
b. 478 nm
c. 777 nm
d. 380 nm
b
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Energy balance in the Sun refers to a balance between ________
A) the force of gravity pulling inward and the force due to pressure pushing outward B) the amount of energy the Sun radiates into space and the amount of energy that reaches Earth C) the rate at which fusion generates energy in the Sun's core and the rate at which the Sun's surface radiates energy into space D) the mass that the Sun loses each second and the amount of mass converted into energy each second
An extremely large collection of stars bound together by gravitational attraction and occupying a huge volume of space is called a(n) ______________
Fill in the blank(s) with correct word
An electron, starting from rest and moving with a constant acceleration, travels 2.0 cm in 5.0 ms. What is the magnitude of this acceleration?
a. 2.5 km/s2 b. 0.80 km/s2 c. 1.6 km/s2 d. 1.3 km/s2 e. 3.2 km/s2
Instantaneous speed and average speed are equal
a. always. b. for motion at constant speed. c. for accelerated motion. d. never.