The current-voltage graph for a device is shown in figure. The resistance is negative in region.
1. AB
2. BC
3. ABC
4. None of these
The current-voltage graph for a device is shown in figure. The resistance is negative in region.
1. AB
2. BC
3. ABC
4. None of these
Subtopic: Derivation of Ohm's Law |
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Silver and copper voltmeters are connected in parallel with a battery of emf 12 V. In 30 min 1 g of silver and 1.8 g of copper are liberated. The energy supplied by the battery is
1. 720 J
2. 2.41 J
3. 24.12 J
4. 4.34 × 104 J
Subtopic: Heating Effects of Current |
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At a specific instant emission of radioactive compound is deflected in a magnetic field. The compound can emit
1. Aelectron
2. protons
3. H2+
4. neutrons
Subtopic: Lorentz Force |
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A magnet is cut in three equal parts by cutting it perpendicular to its length. The time period of original magnet is T0 in a uniform magnetic field B. Then, the time period of each part in the same magnetic field is
1. 
4. None of these
Subtopic: Bar Magnet |
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A 50 Hz AC current of crest value 1 A flows through the primary of a transformer. If the mutual inductance between the primary and secondary be 0.5 H, the crest voltage induced in the secondary is
1. 75 V
2. 150 V
3. 100 V
4. None of these
Subtopic: Mutual Inductance |
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If the length and area of cross-section of a conductor are doubled, then its resistance will be
1. unchanged
2. halved
3. doubled
4. quadrupled
Subtopic: Derivation of Ohm's Law |
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A source of light lies on the angle bisector of two plane mirrors inclined at angle θ. The values of θ, so that the light reflected from one mirror does not reach the other mirror will be
1. 
4. None of the above
Subtopic: Reflection at Plane Surface |
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A ruby laser produces radiations of wavelengths, 662.6 nm in pulse whose duration are 10–9 s. If the laser produces 0.39 J of energy per pulse, how many photons are produced in each pulse?
1. 1.3 × 109
Subtopic: Photoelectric Effect: Experiment |
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Balmer gives an equation for wavelength of visible radiation of H– spectrum as \(\lambda=\frac{k n^{2}}{n^{2}-4}\). The value of k in terms of Rydberg’s constant R is
1. R
2. 4R
3. \(R \over 4\)
4. \(4 \over R\)
Subtopic: Spectral Series |
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From NCERT
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and 
are electron and hole mobility, E be the applied electric field, the current density 
for intrinsic semiconductor is equal to
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