NET, IAS, State-SET (KSET, WBSET, MPSET, etc.), GATE, CUET, Olympiads etc.: Physics MCQs (Practice_Test 9 of 35)
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- An electron having kinetic energy T is moving in a circular orbit of radius R perpendicular to a uniform Magnetic induction B. If kinetic energy is doubled and magnetic induction is tripled, The radius will become
- R ′
- R ′
- R ′
- R ′
- If in the first Bohr orbit of a hydrogen atom the total energy of the electron is-21.76 × 10 − 19 J, then its potential energy will be
- -43.52 × 10 − 19 J
- -21.76 × 10 − 19 J
- -10.88 × 10 − 19 J
- -13.60 × 10 − 19 J
- Consider the following substances, which are frequently used as a source of electrons:
- Magnesium
- Calcium
- Tungsten
- Platinum
- The correct sequence of the above substances in increasing order of their work functions is
- 1,2, 3,4
- 2,1, 3,4
- 2,1, 4,3
- 1,2, 4,3
- The de-Broglie wavelength of material particles which are in thermal equilibrium at temperature T is
- h⟋sqrt 2mkT
- h⟋sqrt 2 mkT
- h-mkT
- h⟋sqrt2 kT
- The phase velocity (Vp) and the group velocity (Vg) of a de-Broglie wave, in free space (speed of light is c) are related as
- Vp⟋Vg = sqrt2
- Vp. Vg = C2
- Vp⟋Vg = 0.5
- Vp Vg = 2C2
- In Compton scattering, the incident photon will lose maximum energy if it is scattered at an angle of:
- 0
- 60
- 90
- 180
- In one of the radioactive decay chains we come across the element 22688 Ra. The final product of the chain is 20682 Pb. The number of a and b-is emitted
- 3 a and 6b-
- 4 a and 5b-
- 5 a and 4b-
- 6 a and 6b-
- At time t. = 0, N1 nuclei of decay constant l1 and N2 nuclei of decay constant l2 are mixed. The decay rate of the mixture is
- N1 N2 e- (l1 + l2) t
- (N1⟋N2) e- (l1 − l2) t
- (N1 N2 e-l1t + N2 l2 e-l 2t)
- N1⟋N2 e- (l1 + l2) t
- The nuclear reaction is an example of
- nuclear chain reaction
- successive disintegration
- pair production
- artificial radioactivity
- Which one of the following particles is a lepton?
- Neutron
- Proton
- Electron
- Lambda
- Match List I with List II and select the correct answer:
Table Supporting: NET, IAS, State-SET (KSET, WBSET, MPSET, Etc.) , GATE, CUET, Olympiads Etc. : Physics MCQs (Practice_Test 9 of 35) List-I (Process) List-II (Approximate Energy released in mV) - Fission of one uranium nucleus
- Formation of one helium nucleus by Fission
- Formation of a compound nucleus
- Formation of a deuteron by the
- Energy 2
- Energy 8
- Energy 200 by the capture of a neutron
- Energy 28 captures of a neutron by a proton
- A
- B
- C
- D
- 3
- 4
- 2
- 1
- 2
- 4
- 1
- 3
- 4
- 2
- 3
- 1
- 3
- 1
- 2
- 4
- Under space charge condition with the plate voltage Eb = 100 V and the permanence K = 104 (In S. I unit) , the plate current in a diode will be
- 10 − 6 mA
- 10 mA
- 102 mA
- 106 mA