MCQ
Armature current in dc motor will be maximum when
- AMotor has acquired maximum speed
- BMotor has acquired intermediate speed
- ✓Motor has just started moving
- DMotor is switched off
✓
Answer
Correct option: C.
Motor has just started moving
c
(c)Motor e.m.f. equation ${E_b} = V - {I_a}{R_a}$
(c)Motor e.m.f. equation ${E_b} = V - {I_a}{R_a}$
At starting ${E_b} = 0,$ so ${I_a}$will be maximum.
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
A fish in an aquarium, $30\,cm$ deep in water can see a light bulb kept $50\,cm$ above the surface of water. The fish can also see the image of this bulb in the reflecting bottom surface of the aquarium. Total depth of water is $60\,cm$. Then the apparent distance between the two images seen by the fish is $(\mu _w = 4/3)$
→Which of the following figures correctly depicts the direction of magnetic field of a current-carrying coil ?
When a hydrogen atom is raised from the ground state to an excited state
A proton and a deutron $( q =+ e , m=2.0 u )$ having same kinetic energies enter a region of uniform magnetic field $\vec{B},$ moving perpendicular to $\vec{B}$. The ratio of the radius $r_d$ of deutron path to the radius $r_p$ of the proton path is:
→Which of the following waves have the maximum wavelength
The velocity of a bullet is reduced from $200\,m/s$ to $100\,m/s $ while travelling through a wooden block of thickness $10\,cm$. The retardation, assuming it to be uniform, will be
→A conducting rod of mass $m$ and length $l$ is free to move without friction on two parallel long conducting rails, as shown below. There is a resistance $R$ across the rails. In the entire space around, there is a uniform magnetic field $B$ normal to the plane of the rod and rails. The rod is given an impulsive velocity $v_0$ Finally, the initial energy $\frac{1}{2} m v_0^2$
→A container with insulating walls is divided into two equal parts by a partition fitted with a valve. One part is filled with an ideal gas at a pressure $P$ and temperature $T$, whereas the other part is completely evacuated. If the valve is suddenly opened, the pressure and temperature of the gas will be
→A heavy iron bar, of weight $\mathrm{W}$ is having its one end on the ground and the other on the shoulder of a person. The bar makes an angle $\theta$ with the horizontal. The weight experienced by the person is:
→In the figure the potentiometer wire of length $l =100\, cm$ and resistance $9\Omega$ is joined to a cell of emf $E_1 = 10V$ and internal resistance $r_1 = 1\Omega $. Another cell of emf $E_2 = 5\, V$ and internal resistance $r_2 = 2 \Omega $ is connected as shown. The galvanometer $G$ will show no deflection when the length $AC$ is ............... $cm$
→