Magnetism And Matter — Physics STD 12 Science — Question

When a forward bias is applied to a p-n junction, it

A concave and convex lens have the same focal length of 20 cm and are put into contact to form a lens combination. The combination is used to view an object of 5 cm length kept at 20 cm from the lens combination. As compared to the object, the image will be(a) Magnified and inverted(b) Reduced and erect (c) Of the same size as the object and erect(d) Of the same size as the object but inverted

Equivalent energy of mass equal to 1 a.m.u. is(a) 931 KeV(b) 931 eV(c) 931 MeV(d) 9.31 MeV

The impurity atoms which are mixed with pure silicon to make a P-type semiconductor are those of(a) Phosphorus(b) Boron(c) Antimony(d) Copper

The introduction of a grid in a triode valve affects plate current by (a) Making the thermionic emission easier at low temperature(b) Releasing more electrons from the plate(c) By increasing plate voltage(d) By neutralising space charge

Two bullets are fired simultaneously, horizontally and with different speeds from the same place. Which bullet will hit the ground first?

1. The faster one.
2. The slower one.
3. Both will reach simultaneously.
4. Depends on the masses.

An oscillator is nothing but an amplifier with(a) Positive feed back(b) Large gain(c) No feedback(d) Negative feedback

The wavelength of light visible to eye is of the order of