- A$\pi$
- B$\pi / 2$
- C$3 \pi / 2$
- ✓$2 \pi$
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To observe diffraction the size of an obstacle
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(a) Should be of the same order as wavelength |
(b) Should be much larger than the wavelength |
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(c) Have no relation to wavelength |
(d) Should be exactly |
Photo cell is a device to
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(a) Store photons |
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(b) Measure light intensity |
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(c) Convert photon energy into mechanical energy |
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(d) Store electrical energy for replacing storage batteries |
The rays of different colours fail to converge at a point after going through a converging lens. This defect is called:
Focal length of a converging lens in air is R. If it is dipped in water of refractive index 1.33, then its focal length will be around (Refractive index of lens material is 1.5)
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(a) R |
(b) 2R |
(c) 4R |
(d) R / 2 |
If no external voltage is applied across P-N junction, there would be
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(a) No electric field across the junction |
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(b) An electric field pointing from N-type to P-type side across the junction |
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(c) An electric field pointing from P-type to N-type side across the junction |
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(d) A temporary electric field during formation of P-N junction that would subsequently disappear |