A photograph of a bacteria enlarged 50,000 times attains a length of 5 cm as shown in the diagram. What is the actual length of the bacteria? If the photograph is enlarged 20,000 times only, what would be its enlarged length?

The breadth of a rectangle is 5 cm. and its length is 3 times of the breadth. What is the perimeter of the rectangle?

A steel tape 1m long is correctly calibrated for a temperature of 27.0 ^@C . The length of a steel rod measured by this tape is found to be 63.0 cm on a hot day when the temperature is 45.0 ^@C . What is the actual length of the steel rod on that day? What Is the length of the same steel rod on a day when the temperature is 27.0 ^@C ? Coefficient of linear expansion of steel = 1.20xx10^-5 K^-1 .

A converging lens has focal length of 20 cm in air. It is made of a material of refractive index 1.6. If it is immersed in a liquid of refractive index 1.3, what will be its new focal length?

The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

The radius of curvature of a spherical mirror is 20 cm. What is its focal length?

A brass rod of length 50 cm and diameter 3.0 mm is joined to a steel rod of the same length and diameter. What is the change in length of the combined rod at 250 ^@C , if the original lengths are at 40.0 ^@C ? Is there a ‘thermal stress’ developed at the junction? The ends of the rod are free to expand (Co-efficient of linear expansion of brass = 2.0 xx 10^-5K^-1 steel = 1.2 xx 10^-5 K^-1) .

A spiral is made up of successive semicircles,with centers alternately at A and B,starting with centre at A,of radio 0.5 cm,1.0 cm,1.5 cm,2.0 cm,….as shown in fig.What is the total length of such a spiral made up of thirteen consecutive semicircles (Take pi=22/7 )

A 5m 60 cm high vertical pole caste a shadow 3m 20 cm long. Find at the same time (i) the length of the shadow cast by another pole 10 m 50 cm high (ii) the height of apole which caste a shadow 5m long.