(a) A sliding bar in figure a has a length of 0.487 m and moves at 2.25 m/s in a

Question

(a) A sliding bar in figure a has a length of 0.487 m and moves at 2.25 m/s in a magnetic field of magnitude 0.232 T. Using the concept of motional emf, find the induced voltage in the moving rod. V

(b) If the resistance in the circuit is 0.734 ?, find the current in the circuit and the power delivered to the resistor. (Note: The current, in this case, goes counterclockwise around the loop.) I = A = W

(c) Calculate the magnetic force on the bar. magnitude N

(d) Use the concepts of work and power to calculate the applied force.

Suppose the current suddenly increases to 1.86 A in the same direction as before, due to an increase in speed of the bar.

(a) Find the emf induced in the rod. ?new = V

(b) Find the new speed of the rod. vnew = m/s

Explanation / Answer

motional emf means that

induced voltage = mag field * length of rod * speed = 0.232 * 0.487 * 2.25 =

= 0.2542 Volts

current = voltage / resistance = 0.2542 / 0.734 = 0.3463 amps

power = i^2 R = 0.3463^2 * 0.734 = 0.08805 Watts

mag force = mag field * current * length = 0.232 * 0.3463 * 0.487 = 0.03913 Newtons

Since the bar moves at constant speed, applied force also equals 0.03913 Newtons

If current increases to 1.86 A

new emf = current * resistance = 1.86 * 0.734 = 1.365 Volts

and speed = emf / mag field * length = 1.365 / 0.232 * 0.487 = 12.08 m/s

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