Science
(a) Write the relationship between resistivity and resistance of a cylindrical conductor of length l and area of cross-section A. Hence derive the SI unit of resistivity.
(b) Why are alloys used in electrical heating devices?
Related Questions
Draw ray diagrams to show the nature, position and relative size of the image formed by a convex mirror when the object is placed
(a) at infinity and
(b) between infinity and pole P of the mirror.
Consider the following electric circuit :
Calculate the values of the following :
(a) The total resistance of the circuit
(b) The total current drawn from the source
(c) Potential difference across the parallel combination of 10 Ω and 15 Ω resistors
(a) Draw two isomeric structures of Butene (C4H8)
(b) Name the following compounds :
(c) Write the chemical equations for the following reactions. Mention one essential condition each for these reactions to take place.
- Ethanol undergoes complete oxidation
- Propene undergoes hydrogenation
- Ethanoic acid reacts with ethanol
(a) A carbon compound X is a good solvent. On reaction with sodium, X forms two products Y and Z. Z is used to convert vegetable oil into vegetable ghee. Identify and name X, Y and Z. Also write the equation of reaction of X with sodium to justify your answer.
(b) Write chemical equation to show what happens when ethanol :
- burns in oxygen/air.
- is heated at 443 K in excess conc. H2SO4.
- reacts with acidified potassium dichromate.