Answer the following questions: A high tension (HT) supply of, say, 6 kV must have a very large internal resistance. Why?

Answer the following questions: A low voltage supply from which one needs high currents must have very low internal resistance. Why?

A low voltage supply from which one needs high currents must have very low internal resistance. Why?

Long Answer Questions Five mark Each QUESTIONS FROM CBSE BOARD EXAMINATIONS : A flower of tomato plant following the process of sexual reproduction produces 240 viable seeds. Answer the following questions giving reasons: (a) What is the minimum number of pollen grains that must have been involved in the pollination of its pistil? (b) What would have been the minimum number of ovules present in the ovary? (c) How many megaspore mother cells were involved? (d) What is the minimum number of microspore mother cells involved in the above case? (e) How many male gametes were involved in this case?

Answer the following questions: Why must both the objective and the eyepiece of a compound microscope have short focal lengths?

Read the given passage and answers following questions : Thomas Graham in 1861, during his work on diffusion found that certain substances such as gelatin, albumin, glue,etc. Diffused at very low rate and were called colloids. The colloid particles have the size in the range of 1 to 100nm consisting of dispersed phase and dispersion medium. The dispersed phase or dispersion medium may be solid, liquid or even a gas. Depending upon the nature of dispersion medium or dispersed phase, 8 types of systems are possible except for a gas dispersed in another gas because the gases are completely miscible with each other. The substances which have strong interaction with the dispersion medium are called lyophilic colloids while those which do not pass into colloidal state readily are called lyophobic colloids. Lyophobic sols are much less stable and are irreversible. Answer the following questions : Which substances have strong interactions with dispersion medium?

Read the given passage and answers following questions : Thomas Graham in 1861, during his work on diffusion found that certain substances such as gelatin, albumin, glue,etc. Diffused at very low rate and were called colloids. The colloid particles have the size in the range of 1 to 100nm consisting of dispersed phase and dispersion medium. The dispersed phase or dispersion medium may be solid, liquid or even a gas. Depending upon the nature of dispersion medium or dispersed phase, 8 types of systems are possible except for a gas dispersed in another gas because the gases are completely miscible with each other. The substances which have strong interaction with the dispersion medium are called lyophilic colloids while those which do not pass into colloidal state readily are called lyophobic colloids. Lyophobic sols are much less stable and are irreversible. Answer the following questions : How many types systems are possible depending upon the nature of dispersion medium?

Direction. In the follwing questions, a statement of assertion is followed by a statement of reason. While answering a question, you are required to choose the correct are out of the given four responses and mark it as (A). If both assertion and reason are true and reason is the correct explanation of the assertion, (B) if both assertion and reason are true but reason is not correct explanation of the assertion. (C) if asssertion is true, but reason if false, (D) if both assertion and reason are false Assertion : Manganin or constantan is used for making standard resistances. Reason : Their resistivity is high, while temperature coefficient is low.

Sangeeta's gardner was suffereing from high blood pressure but he was not caring for his health. One day Sangeeta took him to the doctor. The doctor advised him to take less quantity of salt in his diet. Sangeeta suggested gardner's wife to cook food for her husband with very little salt. Answer the following questions: Why did the doctor advise Sangeeta's gardner to take less quantity of salt?

Direction. In the follwing questions, a statement of assertion is followed by a statement of reason. While answering a question, you are required to choose the correct are out of the given four responses and mark it as (A). If both assertion and reason are true and reason is the correct explanation of the assertion, (B) if both assertion and reason are true but reason is not correct explanation of the assertion. (C) if asssertion is true, but reason if false, (D) if both assertion and reason are false Assertion :the electric bulb glows immedicately, when switched on. Reason : The drift velocity of electrons in a metallic wire is very high.