For which position of the object does a convex lens form a virtual and erect image? Explain with the help of a ray diagram.

Explain how the sex of the child is determined at the time of conception in human beings.

Mention the total number of chromosomes along with sex chromosomes that are present in a human female and a human male. Explain how in sexually producing organisms the number of chromosomes in the progeny remains the same as that of the parents.

(i) Define the term ‘volt’.

(ii) State the relation between work, charge and potential difference for an electric circuit. Calculate the potential difference between the two terminals of a battery if 100 joules of work is required to transfer 20 coulombs of charge from one terminal of the battery to the other.

OR

(i) Define the term ‘coulomb’.

(ii) State the relationship between the electric current, the charge moving through a conductor and the time of flow.

Calculate the charge is passing through an electric bulb in 20 minutes if the value of current is 200 mA.

AB is a current-carrying conductor in the plane of the paper as shown in the figure. What are the directions of magnetic fields produced by it at points P and Q? Given r₁ > r₂, where will the strength of the magnetic field be larger?