An alternating voltage \( V = V_0 \sin(\omega t + \pi/2) \) is applied across an ac circuit. As a result, a current \( I = I_0 \sin(\omega t + \pi/6) \) flows in it. The power factor of the circuit is

The electric potential at a point P due to a point charge of \( 9 \, \mu C \) located 10 cm away from point P is

In a semiconductor let the number of charge carriers be n and the average drift speed be v. An electric field is applied to it. If we increase the temperature of this semiconductor then :

A p-n junction can act basically as

The atomic hydrogen emits a line spectrum consisting of different series. The ratio of frequencies of the first line in Lyman and Balmer series is :

From the following, choose the element for impurity atoms with which pure silicon should be doped to make it a p-type semiconductor:

The magnetic flux through a coil perpendicular to the plane is varying according to the relation \( \phi = (7t^3 + 3t^2 - 2t - 2) \, \text{Wb} \). If the resistance of the coil is \( 10\Omega \), the induced current through the coil at t = 2 s, will be

The area bounded by \(y^2=4 x\) and its latus rectum and \(x\)-axis in the first quadrant is:

Who gave the 'chromosomal theory of inheritance'?

Which of the following is not a sexually transmitted disease?

Which of the following organism does not show 'XO' condition chromosomes?

If the matrix \(\left[\begin{array}{ccc}3 & 2 a & -5 \\ 4 & 0 & b \\ -5 & 3 & 10\end{array}\right]\) is symmetric, then the value of \(5 a+2 b\) is :

Read the passage carefully and give the answers to the question :
Does the number of species in a community really matter to the functioning of the ecosystem? This is a question for which ecologists have not been able to give a definitive answer. For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with less species. According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species described so far is more than 1.5 million.
The following are the various hypotheses proposed in explaining the greatest biological diversity in tropics except :