In a uniform magnetic field, an -shaped metal frame is located perpendicular to the plane of the conductor and varying with time at the rate (dB /dt)=0.20 T/s. A conducting connector starts moving with an acceleration a = 30 cm/s along the parallel bars of the frame. The length, l of the conductor is equal to 44 cm. If at the moment t = 0, the loop area and magnetic induction are equal to zero, then the emf induced in the loop t = 1s after the beginning of motion is
6 × 10-4 V
8 × 10-2 V
6 × 10-2 V
12 × 10-3 V
Two charges q and -3q are placed fixed on X-axis separated by distance d. Where should a third charge 2q be placed such that it will not experience any force?
A current I= 5.0 A flows along a thin wire shaped as shown in given figure. The radius of the curved part of the wire is equal to R = 120 mm and the angle 2 = 90°. Find the magnetic induction of the field at point O.
4.2 × 10-4 T
8.8 × 10-5 T
2.8 × 10-4 T
4.2 × 10-3 T
The activity of a radioactive element decreases to one third of the original activity I0 , in a period of 9 years. After a further lapse of 9 years, its activity will be
I0
(2/3) I0
I0 / 9
I0 / 6
A symmetric double convex lens is cut in two equal parts by a plane perpendicular to the principle axis. If the power of original lens is 4D, then the power of a cut lens will be
2D
3D
4D
8D
A.
2D
When a bi-convex lens is cut perpendicularly to the principal axis, it will become a piano-convex lens.
Focal length of bi-convex lens
For plano-convex lens
On comparing Eqs. (i) and (ii) , we see the focal length becomes double.
As power of lens,
Hence, power will become half.
∴ New power = = 2 D
The maximum number of possible interference maxima for slit separation equal to twice the wavelength in Young's double-slit experiment, is
infinite
five
three
zero
If Mo is the mass of an oxygen isotope , Mp and Mn are the masses of a proton and a neutron, respectively, the nuclear binding energy of the isotope is
(Mo − 8Mp) c2
(Mo − 8Mp − 9Mn) c2
Moc2
(Mo − 17Mn) c2
A fish, looking up through the water sees the outside world contained in a circular horizon. If the refractive index of water is 4/3 and the fish is 12cm below the surface of water, the radius of the circle in centimeter is
12 × 3 ×
12 × 3 ×
To get an output y = 1 from the circuit shown the inputs A, B and C must be respectively.
0, 1, 0
1, 0, 0
1, 0, 1
1, 1, 0
If the bindings energy of the electron in a hydrogen atom is 13.6 eV, the energy required to remove the electron from the first excited state of Li++ is
30.6 eV
13.6 eV
3.4 eV
6.8 eV