Dual Nature of Radiation and Matter — Physics STD 12 Science — Question

In a parallel plate condenser, the radius of each circular plate is 12 cm  and the distance between the plates is 5mm. There is a glass slab of 3mm  thick and of radius 12 cm  with dielectric constant 6 between its plates. The capacity of the condenser will be

(a) 144

(b) 40 pF

(c) 160 pF

(d) 1.44 μF

The energy gap in case of which of the following is less than 3eV?

In physics, chemistry, and electronic engineering, _______________ is the lack of an electron at a position where one could exist in an atom or atomic lattice.

In the disintegration series   The value of Z and A respectively will be

(a) 92, 236

(b) 88, 230

(c) 90, 234

(d) 91, 234

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

A coil of wire having finite inductance and resistance has a conducting ring placed coaxially within it. The coil is connected to a battery at time t = 0, so that a time-dependent current   starts flowing through the coil. If   is the current induced in the ring. and B(t) is the magnetic field at the axis of the coil due to , then as a function of time (t > 0), the product I₂ (t) B(t)

(a) Increases with time	(b) Decreases with time
(c) Does not vary with time	(d) Passes through a maximum

In alternating current.

he half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its  th part

(a) 12 h

(b) 16 h

(c) 48 h

(d) 192 h

A star which appears blue will be

(a) As hot as the sun	(b) Cooler than the sun
(c) Very cold indeed	(d) Much hotter than the sun

The reason of seeing the Sun a little before the sunrise is

(a) Reflection of the light	(b) Refraction of the light
(c) Scattering of the light	(d) Dispersion of the light