Current Electricity — Physics STD 12 Science — Question

A diverging lens of focal length 20cm and a converging mirror of focal length 10cm are placed coaxially at a separation of 5cm. Where should an object be placed so that a real image is formed at the object itself?

What is the process of spontaneous disintegration of an element called?

For transistor action, which of the following statements are correct:

1. Base, emitter and collector regions should have similar size and doping concentrations.
2. The base region must be very thin and lightly doped.
3. The emitter junction is forward biased and collector junction is reverse biased.
4. Both the emitter junction as well as the collector junction are forward biased.

A particle executing simple harmonic motion comes to rest at the extreme positions. Is the resultant force on the particle zero at these positions according to Newton's first law?

When a charged particle moves in a magnetic field normally; what quantity changes the particle’s speed, particle’s energy, path of motion of the particle?

Find two paramagnetic substances from the list below: Sodium (Na), Bismuth (Bi), Copper (Cu), Aluminium (Al), Lead (Pb).

Draw the pattern of electric field lines, when a point charge –Q is kept near an uncharged conducting plate.