Atoms — Physics STD 12 Science — Question

Magnetic fields at two points on the axis of a circular coil at a distance of 0.05m and 0.2m from the centre are in the ratio 8 : 1. The radius of the coil is(a) 1.0 m (b) 0.1 m(c) 0.15 m(d) 0.2 m

A hollow metal sphere of radius 5cm is charged such that the potential on its surface is 10V. The potential at a distance of 2cm from the centre of the sphere(a) Zero(b) 10 V(c) 4 V(d) 10/3 V

The shortest wavelength in Balmer’s series for Hydrogen atom is ...A... and this is obtained by substituting ...B ... in Balmer’s formula. Here, A and B refer to?

A proton beam is going from north to south and an electron beam is going from south to north. Neglecting the earth's magnetic field, the electron beam will be deflected

Assertion  :   A metal piece and a non-metal (stone) piece are dropped from the same height near earth’s surface. Both will reach the earth’s surface simultaneously.
Reason       : There is no effect of earth’s magnetic field on freely falling body.(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 capacitors of capacitances 3 μF  and 6 μF  are charged to a potential of 12 V each. They are now connected to each other, with the positive plate of each joined to the negative plate of the other. The potential difference across each will be (a) 6 volt(b) 4 volt(c) 3 volt (d) Zero

A tuning fork of frequency 480Hz is used to vibrate a sonometer wire having natural frequency 240Hz. The wire will vibrate with a frequency of:

1. 240Hz
2. 480Hz
3. 720Hz
4. Will not vibrate.

According to Biot-Savart's law magnetic field at a point due to a current carrying elements depends upon distance of the point from the element as :