The focal length of the objective lens of a telescop is 50 cm. If the magnification of the telescope is 25 then the focal length of the eye-piece is:

• 12.5 cm

• 5 cm

• 2 cm

• 10 cm

12.

Which one of the following forces is non-central and non-conservative?

• Frictional force

• Electric force

• Gravitational force

• Mechanical force

Suppose there are two planets, 1 and 2, having the same density but their radii are R₁ and R₂ respectively, where R₁ > R₂. The accelerations due to gravity on the surface of these planets are related as:

• g₁ > g₂

• g₁ < g₂

• g₁ = g₂

• Can't say ayntihing

The Sun is seen little before it rises and for a short while after it sets. This is because of:

• total internal reflection

• atmospheric refraction

• apparent shift in the direction of Sun

• dispersion

1 dyne (a unit of force in CGS system) equals to:

• 10³ g cm/s²

• 10^-3 g cm/s²

• 10⁵ kg m/s²

• 10^-5 kg m/s²

The figure shown above gives the time (t) versus position (x) graphs of three objects A, B and C. Which one of the following is the correct relation between their speeds V_A , V_B and V_C respectively at any instant (t > 0)?

• V_A < V_B < V_C

• V_A > V_B > V_C

• V_A = V_B = V_C ≠ 0

• V_A = V_B = V_C = 0

In the given velocity (V) versus time (t) graph, accelerated and decelerated motions are respectively represented by line segments:

• CD and BC

• BC and AB

• CD and AB

• AB and CD

Which one of the following statements regarding a thermos flask is NOT correct?

• The walls of flask are separated by vacuum and made of glass which is a poor conductor of heat.

• The glass walls themselves have shiny surfaces

• The surface of inner wall radiates good amount of heat and the surface of outer wall absorbs some of the heat that is radiated from the inner wall.

• The cork supports are poor conductors of heat

'Black hole' is a:

• huge black star which has zero acceleration due to gravity on its surface

• star which has moderate acceleration due to gravity on its surface

• star which has collapsed into itself and has large acceleration due to gravity on its surface

• star which has collapsed into itself and has large acceleration due to gravity on its surface

The formula for conversion between Fahrenheit and Celsius is °F = X + ( 1.8 x °C) What is factor X?

• 32

• 22

• 98

• 42