- A5 joule
- ✓5 eV
- C5 erg
- D5 watt
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The minimum intensity of light to be detected by human eye is
. The number of photons of wavelength 5.6
entering the eye, with pupil area
, per second for vision will be nearly
|
(a) 100 |
(b) 200 |
(c) 300 |
(d) 400 |
At room temperature, copper has free electron density of 8.4 per
. The copper conductor has a cross-section of 10–6 m2 and carries a current of 5.4 A. The electron drift velocity in copper is
|
(a) 400 m/s |
(b) 0.4 m/s |
(c) 0.4 mm/s |
(d) 72 m/s |
Match the List I with the List II from the combinations shown
|
(I) |
Presbiopia |
(A) |
Sphero-cylindrical lens |
|
(II) |
Hypermetropia |
(B) |
Convex lens of proper power may be used close to the eye |
|
(III) |
Astigmatism |
(C) |
Concave lens of suitable focal length |
|
(IV) |
Myopia |
(D) |
Bifocal lens of suitable focal length |
|
(a) I-A; II-C; III-B; IV-D |
(b) I-B; II-D; III-C; IV-A |
(c) I-D; II-B; III-A; IV-C |
(d) I-D; II-A; III-C; IV-B |
The temperature coefficient of resistance for a wire is 0.00125/℃. At 300K its resistance is 1 ohm. The temperature at which the resistance becomes 2 ohm is
|
(a) 1154 K |
(b) 1100 K |
(c) 1400 K |
(d) 1127 K |
The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light: