Consider the charge configuration and spherical Gaussian surface as shown in the figure. When calculating the flux of the electric field over the spherical surface the electric field will be due to
|
(a) |
(b) Only the positive charges |
|
(c) All the charges |
(d) + |
(c) All the charges
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A plane electromagnetic wave is incident on a material surface. If the wave delivers momentum p and energy E, then
| (a) p = 0, E = 0 | (b) p ¹ 0, E ¹ 0 | (c) p ¹ 0, E = 0 | (d) p = 0, E ¹ 0 |
In order to obtain a real image of magnification 2 using a converging lens of focal length 20 cm, where should an object be placed
|
(a) 50 cm |
(b) 30 cm |
(c) – 50 cm |
(d) – 30 cm |
The half life of a radioactive element which has only 
of its original mass left after a lapse of 60 days is
|
(a) 12 days |
(b) 32 days |
(c) 60 days |
(d) 64 days |
The continuous X-rays spectrum produced by an X-ray machine at constant voltage has
| (a) A maximum wavelength | (b) A minimum wavelength |
|
(c) A single wavelength |
(d) A minimum frequency |
Assertion : The presence of water molecules makes separation of ions easier in electrolyte.
Reason : The presence of water molecules in electrolyte decreases the resistance of electrolyte.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
In the circuit shown here, E1 = E2 = E3 = 2 V and R1 = R2 = 4 ohms. The current flowing between points A and B through battery E2 is
|
(a) Zero |
(b) 2 amp from A to B |
|
(c) 2 amp from B to A |
(d) None of the above |
