- AElectric field.
- BMagnetic field.
- CNorth field.
- DAll.
Explanation:
Space surrounding a magnet in which magnetic force is executed, is called a magnetic field.
A magnetic field is a vector field that describes the magnetic influence of electrical currents and magnetized materials. In everyday life, the effects of magnetic fields are most readily encountered with nearby permanent magnets, which pull on magnetic materials (such as iron) and attract or repel other magnets.
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The length of a wire of a potentiometer is 100 cm, and the emf of its standard cell is E volt. It is employed to measure the e.m.f of a battery whose internal resistance is 0.5 W. If the balance point is obtained at l = 30 cm from the positive end, the e.m.f. of the battery is (where i is the current in the potentiometer)
|
(a) |
(b) |
(c) |
(d) |
Consider the charge configuration and spherical Gaussian surface as shown in the figure. When calculating the flux of the electric field over the spherical surface the electric field will be due to

|
(a) |
(b) Only the positive charges |
|
(c) All the charges |
(d) + |
A parallel monochromatic beam of light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of incident beam. At the first maximum of the diffraction pattern the phase difference between the rays coming from the edges of the slit is
|
(a) 0 |
(b) |
(c) |
(d) 2 |
Two condensers of capacities 2C and C are joined in parallel and charged upto potential V. The battery is removed and the condenser of capacity C is filled completely with a medium of dielectric constant K. The p.d. across the capacitors will now be
|
(a) |
(b) |
(c) |
(d) |
The dispersive power of the material of lens of focal length 20 cm is 0.08. The longitudinal chromatic aberration of the lens is
|
(a) 0.08 cm |
(b) 0.08/20 cm |
(c) 1.6 cm |
(d) 0.16 cm |
When a plane mirror is rotated through an angle θ then the reflected ray turns through the angle 2θ then the size of the image
| (a) Is doubled | (b) Is halved | (c) Remains the same | (d) Becomes infinite |
electrons reach the anode per second. If the power consumed is 448 milliwatts, then the plate (anode) voltage is
|
(a) 150 V |
(b) 200V |
(c) 14 × 448 V |
(d) 448/14V |