AP EAMCET202123 Aug 2021Evening ShiftPhysicsMagnetic Effects of CurrentActual
The coil of a moving coil galvanometer has an effective area of 4 10⁻² ~m ^2 . It is suspended in a magnetic field of 5 10⁻² ~Wb ~m ⁻² . If the deflection in the galvanometer coil is 0.2 rad , when a current of 5 ~mA is passed through it, then
Options
- Atorsional constant is 8 10⁻⁵ ~N ~m rad ⁻¹
- Bcurrent sensitivity is 40 rad A ⁻¹
- Ctorsional constant is 3 10⁻³ ~N ~m rad ⁻¹
- Dcurrent sensitivity is 40 deg A⁻¹
Correct answer
B. current sensitivity is 40 rad A ⁻¹
Step-by-step solution
Given that, for a moving coil galvanometer, Effective area, A=4 10⁻² ~m ^2 Magnetic field, B=5 10⁻² Wbm ⁻² Angle of deflection, =0.2 rad Electric current, I=5 ~mA =5 10⁻³ ~A By using the relation, N A B I=C [where, C= torsional constant ] C= N A B I By substituting the values, we get C= 4 10⁻² 5 10⁻² 5 10⁻³ 0.2 =5 10⁻⁵ Nm rad ⁻¹ Current sensitivity, S_I= I = 0.2 5 10⁻³ rad / A =40 rad A ⁻¹