Question 3 :
The splitting of white light into several colours on passing through a glass prism is due to -
Question 7 :
Why do high rise buildings have a red light on the top of the building?
Question 8 :
Why are red coloured lights are used in traffic signals to stop the vehicles?
Question 10 :
Which of the following statements is correct regarding the propagation of light of different <span>colors of white light in the air?</span>
Question 11 :
The relation among $u$, $v$ and $f$ for a mirror is:
Question 12 :
Angle which the normal ray makes with the mirror is equal to:
Question 13 :
<span>The angle between the incident ray and the reflecting surface is known as:</span>
Question 14 : <div>Fill in the blank:</div><div><br/></div>The angle of incidence, in a plane mirror, is _______ the angle of reflection.
Question 17 :
When the face is very close to the spoon the image formed by the outside bulged part is?
Question 18 :
How is the angle of incidence related to the angle of reflection ?
Question 19 :
All the distances measured to the ________ of the origin<span> are taken as positive.</span>
Question 20 :
Distances measured perpendicular to and above the principal axis<span> are taken as ________.</span>
Question 22 :
A coil of insulated copper wire is connected to a galvanometer. What would happen if a bar magnet is (i) Pushed into the coil?
Question 23 :
A coil carries a current in a magnetic field. The coil experiences a turning effect. Which device uses this effect?
Question 24 : Fill in the blanks:<div>The force on a linear current carrying conductor in magnetic field is half the maximum value when it makes an angle of  ________ with the magnetic field.<br/></div>
Question 26 :
The number of turns per unit length in a toroid is $10^{3}$ and current flowing in it is $\frac{1}{4\pi}$ ampere, then the magnetic induction produced in it, is :<br/>
Question 28 :
A straight wire carries current toward the east.<br>What is the direction of the magnetic field directly below the wire?
Question 29 :
What happens to the strength of the magnetic field if the number of turns is increased?
Question 32 :
Which of the following is not a disadvantage of building large dams?
Question 34 :
From below which are the properties of good source of energy?<br>
Question 36 :
The best way of dating fossils of recent origin is by
Question 37 :
Which method is used to produce electricity in hydro electric power plant?
Question 40 :
Which of the following sources of energy is used in our daily life?<br>
Question 42 :
An electric iron is connected to the 230 V mains <span>supply. A current of 8 A flows through the iron. How much energy is transferred to the heater each </span>second?
Question 43 :
The current in a car headlamp is $3.0$A when connected to a $12$V battery. What is the resistance of the lamp when it is lit?
Question 44 :
An electrical appliance has a resistance of 4 ohms. When it is connected to a 12 V battery, the number of coulombs passing through it per second is
Question 46 :
If negligibly small current is passed though a wire of length 15 m & resistance of 5 $\Omega$, having uniform cross section of $6 \times 10^{-7} m^2$, then coefficient of resistivity of material is
Question 47 :
The masses of the three wires of copper are in the ratio $1 : 3 : 5$. And their lengths are in the ratio $5 : 3 : 1$. The ratio of their electrical resistance is<br>
Question 48 :
Find the cost of operating an electric toaster for $2\ hrs$, if it draws a current of $8\ A$ on a $110\ V$ circuit. The cost of electric energy is $Rs\ 2.5/\ kWh$.
Question 49 :
A square aluminium rod is 1 m long and 5 mm on edge. What must be the radius of another aluminium rod whose length is 1 m and which has the same resistance as the previous rod ?
Question 50 :
A material $\mathrm{B}$' has twice the specific resistance of $\mathrm{A}'$. A circular wire made of $\mathrm{B}$' has twice the diameter of a wire made of $\mathrm{A}'$. Then for the two wires to have the same resistance, the ratio $P_{\mathrm{A}}/P_{\mathrm{B}}$ of their respective lengths must be <br/>
