MCQ
Electromotive force of a battery represents:
- AForce.
- BEnergy.
- CElectric potential energy per unit charge.
- DCurrent.
Explanation:
When a voltage is generated by a battery, this generated voltage has been traditionally called an electromotive force or emf. The emf represents electric potential energy per unit charge (voltage) which has been made available to free electrons by the generating mechanism and is not a force.
The term emf is useful to distinguish voltage generated by the battery from those which occur in a circuit as a result of energy dissipation( Like Voltage drop across a resistor).
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Two coherent sources S1 and S2 are separated by a distance four times the wavelength l of the source. The sources lie along y axis whereas a detector moves along + x axis. Leaving the origin and far off points the number of points where maxima are observed is
|
(a) 2 |
(b) 3 |
(c) 4 |
(d) 5 |
A potentiometer is an ideal device of measuring potential difference because
|
(a) It uses a sensitive galvanometer |
|
(b) It does not disturb the potential difference it measures |
|
(c) It is an elaborate arrangement |
|
(d) It has a long wire hence heat developed is quickly radiated |
To form a composite 16Μf, 1000 V capacitor from a supply of identical capacitors marked 8 μF, 250 V we require a minimum number of capacitors
|
(a) 40 |
(b) 32 |
(c) 8 |
(d) 2 |
The current conduction in a discharged tube is due to
|
(a) Electrons only |
(b) +ve ions and electrons |
|
(c) – ve ions and electrons |
(d) + ve ions, – ve ions and electrons |
A point object O is placed on the principal axis of a convex lens of focal length 20 cm at a distance of 40 cm to the left of it. The diameter of the lens is 10 cm. If the eye is placed 60 cm to the right of the lens at a distance h below the principal axis, then the maximum value of h to see the image will be
|
(a) 0 |
(b) 5 cm |
(c) 2.5 cm |
(d) 10 cm |
12 cells each having same emf are connected in series with some cells wrongly connected. The arrangement is connected in series with an ammeter and two cells which are in series. Current is 3 A when cells and battery aid each other and is 2 A when cells and battery oppose each other. The number of cells wrongly connected is
|
(a) 4 |
(b) 1 |
(c) 3 |
(d) 2 |
In a plano-convex lens the radius of curvature of the convex lens is 10 cm. If the plane side is polished, then the focal length will be (Refractive index = 1.5)
|
(a) 10.5 cm |
(b) 10 cm |
(c) 5.5 cm |
(d) 5 cm |