7. When electrons from a heated filament accelerate through vacuum toward a posi

Question

7. When electrons from a heated filament accelerate through vacuum toward a positive plate A. only an electric field will be produced. B. only a magnetic field will be produced. C. electromagnetic waves will be produced. D. static electric and magnetic waves will be produced. E. neither electric nor magnetic fields will be produced. 8. What is the minimum length of a plane mirror in which you can see the half length of your body, L/2, at one time? A, 2.0 L B.1.5L C. 1.0L D.0.50 L E.0.33 L F.0.25 L 9. A ray strikes the interface of air and a medium of refractive index n-1.. What is the angle between the reflected and refracted rays if the incident ray makes an angle of 60° with the medium's surface? (Round off your answer.) A. 70° B. 80° ?. 130? D. 1500 60.0 E. 170F. Not within 3 degrees of any above.

Explanation / Answer

7) answer is c) Electromagnetic waves will be produced

because of electron,electric waves are produced and because of motion of electron ,magnetic waves are produced

hence the answer is C)

8) if you want to see only half length of your body L/2,then minimum length of plane mirror is L/2/2 = L/4 = 0.25L

so correct answer is F) 0.25L

9) Using snell's law

n1*sin(i) = n2*sin(r)

1*sin(90-60) = 1.5*sin(r)

r = 19.5 deg

required angle is 60+(90-19.5) = 130.5 deg

so the answer isC) 130 deg

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