Science
(a) Write the relation between resistance and electrical resistivity of the material of a conductor in the shape of cylinder of length and area of cross-section . Hence derive the SI unit of electrical resistivity. (b) The resistance of a metal wire of length 3 m is 60 Ω. If the area of cross-section of the wire is 4 × 107 m2, calculate the electrical resistivity of the wire. (c) State how would electrical resistivity be affected if the wire (of part 'b') is stretched so that its length is doubled. Justify your answer.
Related Questions
(a) Draw a diagram showing spore formation in Rhizopus and label the (i) reproductive and (ii) non-reproductive parts. Why does Rhizopus not multiply on a dry slice of bread?
(b) Name and explain the process by which reproduction takes place in Hydra.
(a) Define electric power. Express it in terms of potential difference (V) and resistance (R).
(b) An electric oven is designed to work on the mains voltage of 220 V. This oven consumes 11 units of electrical energy in 5 hours. Calculate :
- power rating of the oven
- current drawn by the oven
- resistance of the oven when it is red hot
The metals produced by various reduction processes are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining.
(a) What is the cathode and anode made of in the refining of copper by this process ?
(b) Name the solution used in the above process and write its formula.
(c) How copper gets refined when electric current is passed in the electrolytic cell?
OR
(c) You have two beakers 'A' and 'B' containing copper sulphate solution. What would you observe after about 2 hours if you dip a strip of zinc in beaker 'A' and a strip of silver in beaker ‘B’? Give reason for your observations in each case.
Mendel worked out the rules of heredity by working on garden pea using a number of visible contrasting characters. He conducted several experiments by making a cross with one or two pairs of contrasting characters of pea plant. On the basis of his observations he gave some interpretations which helped to study the mechanism of inheritance.
(a) When Mendel crossed pea plants with pure tall and pure short characteristics to produce F1 progeny, which two observations were made by him in F1 plants?
(b) Write one difference between dominant and recessive trait.
(c) In a cross with two pairs of contrasting characters
RRYY (Round Yellow) X rryy (Wrinkled Green)
Mendel observed 4 types of combinations in F2 generation. By which method did he obtain F2 generation? Write the ratio of the parental combinations obtained and what conclusions were drawn from this experiment.
OR
(c) Justify the statement : "It is possible that a trait is inherited but may not be expressed."