Current Electricity — Physics STD 12 Science — Question

Which of the following are best suited to make the core of a transformer?

In optical instruments, the lenses are used to form images by:

A thin lens made of glass of refractive index 1.5 has a front surface + 11 D power and back surface – 6 D. If this lens is submerged in a liquid of refractive index 1.6, the resulting power of the lens is

(a) – 0.5 D

(b) + 0.5 D

(c) – 0.625 D

(d) + 0.625 D

Some radioactive nucleus may emit

(a) Only one α,β or γ at a time

(b) All the three α,β  and  γ one after another

(c) All the three α,β  and γ  simultaneously

(d) Only α and β  simultaneously

Which of the following has a negative temperature coefficient

(a) C

(b) Fe

(c) Mn

(d) Ag

The curve drawn between velocity and frequency of photon in vacuum will be a

(a) Straight line parallel to frequency axis

(b) Straight line parallel to velocity axis

(c) Straight line passing through origin and making an angle of 45o with frequency axis

(d) Hyperbola

An electron moving with a velocity of 15ms^-1 enters a uniform magnetic field of 0.2 T, along a direction parallel to the field. What would be its trajectory in this field?

The state of charge inside a closed surface is changed in such a way that total charge remains constant, the flow of electric flux from the closed surface:

The gate for which output is high, if at least one input is low is:

In the circuit given E = 6.0 V, R₁ = 100 ohms, R₂ = R₃ = 50 ohms, R₄ = 75 ohms. The equivalent resistance of the circuit, in ohms, is

(a) 11.875

(b) 26.31

(c) 118.75

(d) None of these