Question

Correct statement are :
(a) A.C. meters can measure D.C also
(b) If A.C. meter measures D.C. their scale must be linear and uniform
(c) A.C. meters is based on heating effect of current and D.C. meters is based on average current method
(d) A.C. meter reads rms value of current

• A. a , b
• B. b , c
• C. c, d
• D. a , c , d

Answer 1

Answer: (D)

AC meters are based on heating effect of current. So, their scales are adjusted according to $I_{\text{rms }}^2$ and their scales are non-linear and they read $I_{ms}$ or $v_{mm}$ DC meters measure $<I>$ or $<v>$ and their scales are linear. As for $DC{I}_{rms}=I$, So, $AC$ meters can measure $DC$ but $DC$ meters cant measure $AC$.