Question
When we see an object, the image formed on the retina is:
- Real.
- Virtual.
- Erect.
- Inverted.
Explanation:
The retina acts as a screen in the eye; only real, inverted images can be obtained on the screen.
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A convex lens of ______ focal length gives a greater magnification than lenses of _______ focal length.
Assertion : In Young’s double slit experiment, the fringes become indistinct if one of the slits is covered with cellophane paper.
Reason : The cellophane paper decrease the wavelength of light.
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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 electrical circuit used to get smooth dc output from a rectifier circuit is called
| (a) Oscillator | (b) Filter | (c) Amplifier | (d) Logic gates |
A parallel plate capacitor has a capacity C. The separation between the plates is doubled and a dielectric medium is introduced between the plates. If the capacity now becomes 2C, the dielectric constant of the medium is
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(a) 2 |
(b) 1 |
(c) 4 |
(d) 8 |
Assertion : Only a change in magnetic flux will maintain an induced current the coil.
Reason : The presence of large magnetic flux through a coil maintains a current in the coil if the circuit is continuous.
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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 colour of a star is an indication of its
|
(a) Weight |
(b) Distance |
(c) Surface temperature |
(d) Size |
A permanent magnet
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(a) Attracts all substances |
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(b) Attracts only magnetic substances |
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(c) Attracts magnetic substances and repels all non-magnetic substances |
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(d) Attracts non-magnetic substances and repels magnetic substances |
The electron mobility in N-type germanium is 3900 cm2/v-s and its conductivity is 6.24 mho/cm, then impurity concentration will be if the effect of cotters is negligible
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(a) 1015 cm3 |
(b) 1013 /cm3 |
(c) 1012 /cm3 |
(d) 1016 /cm3 |