Question
6 and 7 please
A certain resistor dissipates electrical energy at a rate of 0.5 W when connected to a 3 V potential difference. When connected to a 1 V potential difference, the rate of electrical energy dissipation is: a) 0.5 W b) 0.167 W c) 1.5 W d) 0.056 W e) none of these At one instant an electron is moving in the x-y plane with a velocity v = v_x x + v_y y, where v_x = 5 times 10^5 m/s and v_y = 3 times 10^5 m/s. A magnetic field whose magnitude is 0.8 T points in the positive x direction. At that instant the magnitude of the magnetic force on the electron is: a)0 b) 2.6 times 10^-14 N c) 3.8 times 10^-14 N d) 6.4 times 10^-14 N e) 1.0 times 10^-13 N
Explanation / Answer
6.
Result : (d) 0.056 W
Explanation :
Power, P = V2/R
P = 0.5 W at V = 3V
At V= 1 V , P = 0.5W/9 = 0.056 W
7. Result : (c) 3.8×10-14 N
Explanation :
Magnetic force F = qV× B
Magnetic force point in positive x direction , hence
F= q vy B
= (1.6×10-19)(3×105)(0.8)
= 3.8×10-14 N