MCQ
When an electron jumps from the fourth orbit to the second orbit, one gets the:
- ASecond line of Paschen series.
- BSecond line of Balmer series.
- CFirst line of Pfund series.
- DSecond line of Lyman series.
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The distance travelled by light in glass (refractive index =1.5) in a nanosecond will be
|
(a) 45 cm |
(b) 40 cm |
(c) 30 cm |
(d) 20 cm |
A radioactive substance has a half life of 60 minutes. After 3 hours, the fraction of atom that have decayed would be
|
(a)12.5% |
(b) 87.5% |
(c) 8.5% |
(d) 25.1% |
In a Young’s double slit experiment, the slit separation is 0.2 cm, the distance between the screen and slit is 1m. Wavelength of the light used is 5000 Å. The distance between two consecutive dark fringes (in mm) is
|
(a) 0.25 |
(b) 0.26 |
(c) 0.27 |
(d) 0.28 |
A divergent lens will produce
|
(a) Always a virtual image |
(b) Always real image |
|
(c) Sometimes real and sometimes virtual |
(d) None of the above |
An electron moving with a uniform velocity along the positive x-direction enters a magnetic field directed along the positive y-direction. The force on the electron is directed along
|
(a) Positive y-direction |
(b) Negative y-direction |
|
(c) Positive z-direction |
(d) Negative z-direction |