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Odd man out

Natural Gas,wind,water,biofuel

An object of 5.0 cm size is placed at a distance of 20.0 cm from a converging mirror of focal length 15.0 cm. At what distance from the mirror should a screen be placed to get the sharp image ? Also calculate the size of the image.

A layer of benzene $(\mu =1.5)$ having thickness $12\text{cm}$ floats in a vessel on water layer $(\mu =4/3)$ having thickness $8\text{cm}$. When viewed from top obliquely, the apparent depth of the bottom of the vessel below the surface of benzene will be

The ion of an element has 3 positive charge, 27 mass-number and 14 neutrons. What is the number of electrons in this ion?

Two objects are placed on the principal axis of a thin converging lens. One is $10cm$ from the lens and the other is on the other side of the lens at a distance of $40cm$ from the lens. The image of both objects are in the same place. The focal length of the lens is (in $cm$).

According to the modified Ampere's circuital law ($i_D=$ displacement current)

Mention two properties of a wave; the property which varies and the other which remains constant when a wave passes from one medium to another.

The energy released from nuclear fission is used to -

After working in the coal mine where did the boy work next and what did he learn?

When a current I flows through a rsistance R for time t, th eelectica energy spent is:
(a) IRt

(b) $I^{2}Rt$

(c) $I{R}^{2}t$

(d) $\frac{I^{2}R}{t}$

Find the cost of heating $4.6\text{kg}$ of water from ${25}^{\circ }\text{C}$ to the boiling point, assuming that no energy is wasted. Electrical energy costs $25\text{Paisa}$ per $\text{kWh}$.

[Take specific heat capacity of water, $s=1{\text{cal g}}^{-1}{}^{\circ }{\text{C}}^{-1}$]

Which of the following statements are true regarding gamma radiation?

A convex lens of power $4\text{D}$ is placed at a distance of $40\text{cm}$ from a wall. At what distance from the lens should a candle be placed so that its image is formed on the wall?

1. 932.58

A person needs a lens of power –5.5 dioptres for correcting his near vision and he needs a lens of power +1.5 dioptre. What is the focal length of the lens required for correcting?

(i) distant vision

(ii) near vision

The coefficient of expansion of an inhomogenous rod changes linearly from ${\alpha }_1$ to ${\alpha }_2$ from one end to other end of the rod. The effective coefficient of linear expansion of the rod is:

A space ranger uses 6 L of fuel over the course of 16 h. The fuel that he uses for each hour is L.

Find the equivalent resistance between the points $A$ and $B$.

The focal length of a normal eye lens is about

Find the ratio of resistances of two copper rods X and Y of lengths 30 cm and 50 cm respectively and having a radii $3cm$ and $2cm$ respectively.

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Two long coaxial and conducting cylinders of radius $a$ and $b$ are separated by a material of conductivity $\sigma$ and a constant potential difference $V$ is maintained between them. Then the current, per unit length flowing in between cylinders is

Notice these words in the poem and guess their meaning from the context

To determine focal length of a concave mirror a student obtains the image of a well lit distant object on a screen. To determine the focal length of the given concave mirror he needs to measure the distance between:

• What is the sound of your school bell?

• Can you make sounds of different bells that you have heard?

• Different bells make different sounds. Try and make the sound of a -

• Write the first letter of each picture given in the box.

A metal of mass $250\text{g}$ is kept at its melting point ${300}^{\circ }\text{C}$. It freezes at the same temperature releasing about $45\text{kJ}$ of energy. Find the specific latent heat of the metal in its S.I. unit.

Why does a driver use a convex mirror instead of a plane mirror as a rear view mirror? Illustrate your answer with the help of a ray diagram.

Why do we need management of natural resource?

Given that P, V and T stand for vapour pressure, volume and temperature, an ideal gas obeys the law -PV α T. If the volume is kept constant, P α T. With decreasing temperature the vapour pressure drops, until P = 0 at some temperature T₀. Since P cannot be less than zero, or negative, T₀ naturally becomes the lowest temperature that we can reach, and can be used as a "natural” lower fixed point while constructing a temperature scale. This is the "absolute zero”, which in the Celsius scale is - 273.15⁰C.

To construct an absolute temperature scale , where the absolute zero is naturally 0. Let us choose the triple point of mercury (-38.8⁰C, at 0.2 mPa) as our upper fixed point, and give assign it a value 100. What will be the boiling point of water on this scale?