Gzb 01 Feb 14

1-In context of transistors, the coefficient hfe is same as beta .

2-In oscillators transistor operates in active mode as it works as amplifier there.

3-(a)In case of photoelectric experiment , if the power of the source is doubled and frequency of the light is also doubled, then saturation photoelectric current still remains unchanged.
3(b)In case of photoelectric experiment, if the source of light is a point source and it is moved to twice distance from the photoelectric plate, the saturation photoelectric current will decrease to one fourth but the stopping potential will remain same

4-In a series RLC ac circuit , quality factor

• decreases if resistance is increased
• decreases if the capacitance is increased
• increases if the self inductance is increased.

5-In series RLC ac circuit, the power factor

• Increases if the resistance increases
• may increase or decrease on increasing the self inductance depending on the value of the source frequency in comparison to the resonance frequency.

6-In hydrogen like atom, if the electron moves to higher energy level, it's kinetic energy decreases by same amount as the total energy increases.

7-In hydrogen like atom, deBroglie wavelength of the electron will be directly proportional to the principal quantum number of the orbit in which the electron is rotating.

8-Two magnets placed at large distance x from one another, exert force and torque on each other.
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9- In the above arrangements, in the first fig, the two magnets repel each other and apply clockwise torque on each other. In the second fig, the two magnets attract each other but will not exert torque. Note that the two magnets exert force on each other which vary as Fourth power of the inverse of their separation.

10-When light wave is reflected from an optically denser medium, it suffers phase change of 180 degree.

11- When a transparent sheet is pasted in front of any one slit in YDSE, then fringes move towards that slit , in this case fringe width remains unchanged but the order of a fringe at given location on the screen , changes by (n-1)t/ wavelength.

12-In amplifies with transistor operating in CE mode, output potential differs in phase by 180 degree with respect to input .

Viresh