- AVariable resistor
- BRheostat
- CCircular coil
- DBoth a and b
Explanation:
It is rheostat

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As shown in the figure a metal rod makes contact and complete the circuit. The circuit is perpendicular to the magnetic field with B = 0.15 tesla. If the resistance is 3Ω, force needed to move the rod as indicated with a constant speed of 2m/sec is

|
(a) 3.75 |
(b) 3.75 |
(c) 3.75 |
(d) 3.75 |
The number of turns and radius of cross-section of the coil of a tangent galvanometer are doubled. The reduction factor K will be
| (a) K |
(b) 2K |
(c) 4K |
(d) K/4 |
A ray of light passes through four transparent media with refractive indices
and
as shown in the figure. The surfaces of all media are parallel. If the emergent ray CD is parallel to the incident ray AB, we must have

|
(a) |
(b) |
(c) |
(d) |
The equivalent resistance of the arrangement of resistances shown in adjoining figure between the points A and B is

|
(a) 6 ohm |
(b) 8 ohm |
(c) 16 ohm |
(d) 24 ohm |
Two lenses of power +12 and – 2 diopters are placed in contact. What will the focal length of combination
|
(a) 10 cm |
(b) 12.5 cm |
(c) 16.6 cm |
(d) 8.33 cm |
The energy of the highest energy photon of Balmer series of hydrogen spectrum is close to
| (a) 13.6 eV | (b) 3.4 eV | (c) 1.5 eV | (d) 0.85 eV |