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The working of optical instruments like camera, microscope, telescope, etc. having glass lenses is based on a phenomenon of light. Identify the phenomenon.
An atomic nucleus 
emits several a and b radiations and finally reduces to 
. It must have emitted
|
(a) 4a and 2b |
(b) 6a and 4b |
(c) 8a and 24b |
(d) 4a and 16b |
A voltmeter has resistance of 2000 ohms and it can measure upto 2V. If we want to increase its range to 10 V, then the required resistance in series will be
|
(a) 2000 Ω |
(b) 4000 Ω |
(c) 6000 Ω |
(d) 8000 Ω |
Assertion : If two long wires, hanging freely are connected to a battery in series, they come closer to each other.
Reason : Force of attraction acts between the two wires carrying current.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
A compass needle will show which one of the following directions at the earth's magnetic pole
| (a) Vertical | (b) No particular direction |
| (c) Bent at 45° to the vertical | (d) Horizontal |
Resistances 
and 
are joined in parallel and a current is passed so that the amount of heat liberated is 
and 
respectively. The ratio 
has the value
|
(a) |
(b) |
(c) |
(d) |
