MCQ
Which instrument is used as the null detector in the Wheatstone bridge?
- AVoltmeter
- BAmmeter
- CGalvanometer
- DMultimeter
Explanation:
A galvanometer is used as the null detector in a Wheatstone bridge. The null point means the situation in which no current flows through the circuit. The galvanometer is used for measuring the current and also to determine the voltage between any two points of the circuit. Galvanometer is used due to its sensitivity and therefore, even small currents can be measured.
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$\text{F}=\frac{\text{K.}(\text{q}_1\times\text{q}_2)}{\text{r}^2}$
This is given by which law?A concave and convex lens have the same focal length of 20 cm and are put into contact to form a lens combination. The combination is used to view an object of 5 cm length kept at 20 cm from the lens combination. As compared to the object, the image will be
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(a) Magnified and inverted |
|
(b) Reduced and erect |
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(c) Of the same size as the object and erect |
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(d) Of the same size as the object but inverted |
A ray of light passes through an equilateral glass prism in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to 3/4 of the angle of the prism. The angle of deviation is
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(a) 45° |
(b) 39° |
(c) 20° |
(d) 30° |
When we touch the terminals of a high voltage capacitor, even after a high voltage has been cut off, then the capacitor has a tendency to
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(a) Restore energy |
(b) Discharge energy |
(c) Affect dangerously |
(d) Both (b) and (c) |
Assertion : A spark occur between the poles of a switch when the switch is opened.
Reason : Current flowing in the conductor produces magnetic field.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
The k line of singly ionised calcium has a wavelength of 393.3 nm as measured on earth. In the spectrum of one of the observed galaxies, this spectral line is located at 401.8 nm. The speed with which the galaxy is moving away from us, will be
|
(a) 6480 km/s |
(b) 3240 km/s |
(c) 4240 km/sec |
(d) None of these |
The relative permeability is represented by mr and the susceptibility is denoted by c for a magnetic substance. Then for a paramagnetic substance
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(a) mr < 1, c < 0 |
(b) mr < 1, c > 0 |
(c) mr > 1, c < 0 |
(d) mr > 1, c > 0 |
A capacitor of capacity C has charge Q and stored energy is W. If the charge is increased to 2Q, the stored energy will be
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(a) 2W |
(b) W/2 |
(c) 4W |
(d) W/4 |