Question

Please answer question (A-C) correctly showing work for thumbs up.

A) The current in an electron beam in a cathode-ray tube is measured to be 70 mA. How many electrons hit the screen in 20.0 s? (e= 1.6 x 10^ -19 C)

a. 2.2 x 10^11 electrons

b. 8.8 x 10^13 electrons

c. 2.2 x 10^15 electrons

d. 8.8 x 10^18 electrons

B) If a metallic wire of cross sectional area 3.0 x 10^-6 m^2 carries a current of 3.0 A and has a mobile charge density of 4.24 x 10^28 carriers/m^3, what is the average drift velocity of the mobile charge carriers? (charge value= 1.6 x10^-19 C)

a. 3.4 x 10^3 m/s

b. 1.7 x 10^3 m/s

c. 1.5 x 10^-4 m/s

d. 2.9 x 10^-4 m/s

C) How long is a wire made from .1 m^3 of copper if its resistance is 8.3 ohms? The resistivity of copper is 1.7 x 10^-5 Ω*m.

a. 7.1 m

b. 1.7 x 10^2 m

c. 2.2 x 10^2 m

d. 3.0 x 10^3 m

Answer 1