Why we need a 5 A fuse for an electric iron which consumes 1 kW power at 220 V?
Voltage, V = 220 V Power, P = 1 kW = 1000 W Fuse current, I = 5 A To find: Current flow in the circuit, I. Solution:... View Article
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State Joule’s law of heating.
Joule’s Law of Heating refers to the heat generated by an electrical conductor is directly proportional to the product of its... View Article
For the combination of resistors shown in the following figure, find the equivalent resistance between M & N.
(a) Given: Resistance of the resistors = R1,R2,R3, and R4 To find: Equivalent resistance, (Req) between M & N. Here, from the figure we can see... View Article
What is sex selective abortion? How does it affect a healthy society? (State any one consequence)
Sex-selective abortion is the method of terminating a pregnancy based upon the predicted sex of the infant (unborn foetus). It... View Article
How do oral contraceptive help in avoiding pregnancies?
Oral contraceptives are tablets that are taken orally and contain small doses of hormones. This prevents the release of eggs... View Article
“Use of a condom is beneficial for both the sexes involved in a sexual act.” Justify this statement giving two reasons.
Use of a condom is beneficial for both the sexes involved in a sexual act, because a condom is the... View Article
Name the parts of flower that develop after fertilization into (i) Seed (ii) Fruit
After fertilization, (i) The ovule develops into a seed. (ii) The ovary develops into a fruit. Fertilization in plants In... View Article
State the significance of pollen tube.
The function of the pollen tube is to carry male gametes towards the ovary through stigma and style. It enters... View Article
Draw a diagram showing germination of pollen on stigma of a flower and mark on it the following organs/parts: (i) Pollen Grain (ii) Pollen tube (iii) Stigma (iv) Female germ cell
Pollen germination starts with the pollen grain landing on stigma. The cell of the pollen grain divides into two cells-... View Article
What happens when the system of blood vessels develop a leak?
When blood vessels or the circulatory vessels get damaged or injured or punctured, blood oozes out into the nearby tissues... View Article
Write the correct sequence of steps followed during journey of oxygen rich blood from lungs to various organs of human body.
The blood from the right atrium enters the right ventricle. Then it reaches pulmonary arteries that carry deoxygenated blood from... View Article
Draw the structure of cyclohexane.
Cyclohexane is a cycloalkane with the molecular formula C6H12. In the structure formula of cyclohexane there are 16 single bonds... View Article
Compare soaps and detergents on the basis of their composition and cleansing action in hard water.
Soaps Detergents Soaps are sodium or potassium salts of long-chain fatty acids / carboxylic acids. Detergents are ammonium or... View Article
Ionic compounds are solids. Give reasons.
Ionic compounds are solids and some what hard because of strong force of attraction between positive and negative ions. Ionic... View Article
By the transfer of electrons, illustrate the formation of bond in magnesium chloride and identify the ions present in this compound.
Magnesium has Atomic Number = 12. Its electronic configuration is 2,8,2. Chlorine has Atomic Number = 17. Its electronic configuration... View Article
Write balanced chemical equations to explain what happens, when (i) Mercuric oxide is heated. (ii) Mixture of cuprous oxide and cuprous sulphide is heated. (iii) Aluminium is reacted with manganese dioxide. (iv) Ferric oxide is reduced with aluminium. (v) Zinc carbonate undergoes calcination.
(i) When mercuric oxide (HgO), a red solid, is heated at a very high temperature, it decomposes to give mercury (Hg),... View Article
A person needs a lens of power + 3D for correcting his near vision and –3D for correcting his distant vision. Calculate the focal lengths of the lenses required to correct these defects.
(b) Given: Power, P1 = +3D (for correcting near vision) Power, P2 = −3D (for correcting distant vision) To find: Focal length of the lenses, f. ... View Article
A person is suffering from both myopia and hypermetropia. (i) What kind of lenses can correct this defect? (ii) How are these lenses prepared?
(a) If a person is suffering from both myopia and hypermetropia. (i) Bifocal lenses can correct this defect. (ii) These... View Article
With the help of labelled ray diagram show the path followed by a narrow beam of monochromatic light when it passes through a glass prism. What would happen if this beam is replaced by a narrow beam of white light?
(a) The labeled ray diagram given below, showing the path followed by a narrow beam of monochromatic light when it... View Article
Give reasons for the following: (i) There is either a convergence or a divergence of magnetic field lines near the ends of a current carrying straight solenoid. (ii) The current carrying solenoid when suspended freely rests along a particular direction. (iii) The burnt out fuse should be replaced by another fuse of identical rating.
(i) There is either a convergence or a divergence of magnetic field lines near the ends of a current-carrying straight... View Article
