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Topic:
Electromagnetism
Question:
The material used in florescent screen of CRO is?
Options:
- Magnesium
- Glass
- Phosphor
- Sodium
Correct Option:
Phosphor
Explanation:
A phosphor, most generally, is a substance that exhibits the phenomenon of luminescence. Somewhat confusingly, this includes both phosphorescent materials, which show a slow decay in brightness (>1 ms), and fluorescent materials, where the emission decay takes place over tens of nanoseconds.
Topic:
Heat & Thermodynamics
Question:
At triple point of water, the pressure of gas is 2680 Pa. By changing T the pressure changed to 4870 Pa. The value of T is?
Options:
- 496 K
- 438 K
- 0
- 438 F
Correct Option:
496 K
Explanation:
p.V = n.R.T
Since volume V and mass hence number of moles is constant:
p/T = n.R/V = constant
=> p1/T1 = p2/T2
=> T2 = T1.p2/p1
T1 is the triple point temperature of water, i.e
T1 = 0.010C = 273.16 K
Hence:
T2 = 273.16 K * 4870Pa/2680Pa = 496.38K
Topic:
Nuclear physics
Question:
The energy obtained in a nuclear reaction is derived from:
Options:
- Mass defect and binding energy
- Fission
- Fusion
- All of these
Correct Option:
All of these
Explanation:
The sum of the individual masses of the parts of a nucleus is less than their mass when they are bound into the nucleus producing mass defect. The mass from the mass defect is converted into the energy that holds the nucleus together and is released in fission. Fusion also produces energy when individual nuclei are forced to combine (fusion) and form new elements in a process that produces energy.