Atoms — Physics STD 12 Science — Question

When a bi-convexo lens of glass with refractive index 1.47 is immersed in a liquid, then it behaves like a plane glass sheet, it means that the refractive index of the liquid is :

Pick the correct options:

A radioactive nucleus  decays to  . Which of the following particles are emitted

(a) One alpha and one electron	(b) Two deuterons and one positron
(c) One alpha and one proton	(d) One proton and four neutrons

A plane electromagnetic wave of frequency 20 MHz travels through a space along x direction. If the electric field vector at a certain point in space is 6V m^-1, what is the magnetic field vector at that point?

A ring of radius R, made of an insulating material carries a charge Q uniformly distributed on it. If the ring rotates about the axis passing through its centre and normal to plane of the ring with constant angular speed ω, then the magnitude of the magnetic moment of the ring is

(a) Qω

(b)

(c) Q

(d)

When a metallic rod falls freely, keeping its length horizontal and parallel to northsouth direction, emf induced across it is __________ .

Two wave pulses travel in opposite directions on a string and approach each other. The shape of one pulse is inverted with respect to the other.

1. The pulses will collide with each other and vanish after collision.
2. The pulses will reflect from each other i.e., the pulse going towards right will finally move towards left and vice versa.
3. The pulses will pass through each other but their shapes will be modified.
4. The pulses will pass through each other without any change in their shapes.

If the wavelength of the first line of the Balmer series of hydrogen is 6561 , the wavelength of the second line of the series should be

(a) 13122

(b) 3280

(c) 4860

(d) 2187

Assertion :   Reduction factor (K) of a tangent galvanometer helps in reducing deflection to current.

Reason     : Reduction factor increases with increase of current.

(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.

(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.

(c) If assertion is true but reason is false.

(d) If the assertion and reason both are false.

Two copper balls, each weighing 10g are kept in air 10 cm apart. If one electron from every  atoms is transferred from one ball to the other, the coulomb force between them is (atomic weight of copper is 63.5)

(a) 2.0

(b) 2.0

(c) 2.0

(d) 2.0