MCQ
Alternating current can not be measured by dc ammeter because
- Aac cannot pass through dc ammeter
- ✓Average value of complete cycle is zero
- Cac is virtual
- Dac changes its direction
✓
Answer
Correct option: B.
Average value of complete cycle is zero
In $d c$ ammeter, a coil is free to rotate in the magnetic field of a fixed magnet.If an alternating current is passed through such a coil, the torque will reverse it's direction each time the current changes direction and the average value of the torque will be zero.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
In a hydrogen atom, an electron of mass $m$ and charge $e$ revolves in an orbit of radius $r$ making $n$ revolutions per second. If the mass of hydrogen nucleus is $M$, the magnetic moment associated with the orbital motion of electron is
→A diverging beam of light from a point source $S$ having divergence angle $\alpha$, falls symmetrically on a glass slab as shown. The angles of incidence of the two extreme rays are equal. If the thickness of the glass slab is $t$ and the refractive index $n$, then the divergence angle of the emergent beam is
→A ball hits a vertical wall horizontally at $10 \mathrm{~m} / \mathrm{s}$ bounces back at $10 \mathrm{m} / \mathrm{s}$
→A simple pendulum is oscillating without damping. When the displacement of the bob is less than maximum, its acceleration vector $\vec{a}$ is correctly shown in
→Angle of prism is A and its one surface is silvered. Light rays falling at an angle of incidence $2 \mathrm{~A}$ on first surface return back through the same path after suffering reflection at second silvered surface. Refractive index of the material of prism is
→From a stationary tank of mass 125000 pound a small shell of mass 25 pound is fired with a muzzle velocity of $1000 \mathrm{ft} / \mathrm{sec}$. The tank recoils with a velocity of
→The length of an iron wire is $L$ and area of cross-section is $A$. The increase in length is $l$ on applying the force $F$ on its two ends. Which of the statement is correct
→The ratio of de-Broglie wavelengths of molecules of hydrogen and helium which are at temperature $27 C$ and $127 C$ respectively is
→A plane mirror is placed at the bottom of the tank containing $a$ liquid of refractive index $\mu . P$ is a small object at a height $h$ above the mirror. An observer $O$-vertically above $P$ outside the liquid see $P$ and its image in the mirror. The apparent distance between these two will be
→Two spheres made of same material have radii in the ratio 1: 2 Both are at same temperature. Ratio of heat radiation energy emitted per second by them is