Two resistances 
and 
when connected in series and parallel with 120 V line, power consumed will be 25 W and 100 W respectively. Then the ratio of power consumed by to that consumed by will be
|
(a) 1 : 1 |
(b) 1 : 2 |
(c) 2 : 1 |
(d) 1 : 4 |
(a) 1 : 1
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The chemical equivalent of copper and zinc are 32 and 108 respectively. When copper and silver voltameter are connected in series and electric current is passed through for sometimes, 1.6 g of copper is deposited. Then, the mass of silver deposited will be
|
(a) 3.5 g |
(b) 2.8 g |
(c) 5.4 g |
(d) None of these |
Fusion reaction takes place at high temperature because
|
(a) Atoms are ionised at high temperature |
|
(b) Molecules break-up at high temperature |
|
(c) Nuclei break-up at high temperature |
|
(d) Kinetic energy is high enough to overcome repulsion between nuclei |
In Young's double slit experiment when wavelength used is 6000 Å and the screen is 40 cm from the slits, the fringes are 0.012 cm wide. What is the distance between the slits
|
(a) 0.024 cm |
(b) 2.4 cm |
(c) 0.24 cm |
(d) 0.2 cm |
The percentage of Sun's total energy which reaches the earth's surface is
|
(a) 10–7 % |
(b) 10–6 % |
(c) 10–3 % |
(d) 10–2 % |
An X-ray tube is operating at 50 kV and 20 mA. The target material of the tube has a mass of 1.0 kg and specific heat 495 J kg-1 
. One percent of the supplied electric power is converted into X-rays and the entire remaining energy goes into heating the target. Then
|
(a) A suitable target material must have a high melting temperature |
|
(b) The average rate of rise of temperature of target would be 2 °C/s |
|
(c) The minimum wavelength of the X-rays emitted is about 0.25 |
|
(d) a, b, c |
The current passing through a choke coil of 5 henry is decreasing at the rate of 2 ampere/sec. The e.m.f. developing across the coil is
|
(a) 10 V |
(b) – 10 V |
(c) 2.5 V |
(d) – 2.5 V |
