SSC JE Electrical Engineering 2011 Paper

Question : 110 of 150

Marks: +1, -0

In an induction type energy meter, everything else remaining game, if the radial distance of the brake magnet poles from the spindle is decreased by 10%, the rotational speed of the dise will approximately

increase by 23.5%
decrease by 10.6%
decrease by 19.4%
increase by 11%

Validate

Solution:

Braking torque produce in energy meter

T_B ∝ ND

D = radial distance of the brake magnet poles from the spindle.

D_1 = 9D

and every thing else remain constant

N_1D_1 = N_2D_2

N D = N_2. 9D.

N_2=N/2=1.1N

So speed will increase by 1190

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