Physics-

#### The distance between a point source of light and a screen which is 60 *cm* is increased to 180 *cm*. The intensity on the screen as compared with the original intensity will be

Physics-General

- 3 times
- (1/9) times
- 9 times
- (1/3) times

#### Answer:The correct answer is: (1/9) times

## Book A Free Demo

+91

Grade*

Select Grade

### Related Questions to study

maths-

The pole of the straight line 9x + y – 28 = 0 with respect to the circle is

The pole of the straight line 9x + y – 28 = 0 with respect to the circle is

maths-General

physics-

#### Three rods of equal length are joined to form an equilateral triangle O is the mid point of Distance remains same for small change in temperature. Coefficient of linear expansion for and is same, but that for is Then

Neglecting and

#### Three rods of equal length are joined to form an equilateral triangle O is the mid point of Distance remains same for small change in temperature. Coefficient of linear expansion for and is same, but that for is Then

physics-General

Neglecting and

physics-

#### A point source causes photoelectric effect from a small metal plate Which of the following curves may represent the saturation photocurrent as a function of the distance between the source and the metal?

#### A point source causes photoelectric effect from a small metal plate Which of the following curves may represent the saturation photocurrent as a function of the distance between the source and the metal?

physics-General

physics-

#### One of the following figures respesents the variation of particle momentum with associated de Broglie wavelength

a)

b)

c)

#### One of the following figures respesents the variation of particle momentum with associated de Broglie wavelength

a)

b)

c)

physics-General

physics-

#### An electric lamp is fixed at the ceiling of a circular tunnel as shown is figure. What is the ratio the intensities of light at base *A* and a point *B* on the wall

and

#### An electric lamp is fixed at the ceiling of a circular tunnel as shown is figure. What is the ratio the intensities of light at base *A* and a point *B* on the wall

physics-General

and

maths-

#### If the line y = x + 3 meets the circle at A and B, then equation of the circle on AB as diameter is

#### If the line y = x + 3 meets the circle at A and B, then equation of the circle on AB as diameter is

maths-General

physics-

#### The figure shows a system of two concentric spheres of radii and and kept at temperatures and respectively. The radial rate of flow of heat in a substance between the two concentric spheres, is proportional to

To measure the radial rate of heat flow, we have to go for integration technique as here the area of the surface through which heat will flow is not constant.

Let us consider an element (spherical shell) of thickness d and radius as shown in figure. Let us first find the equivalent thermal resistance between inner and outer sphere.

Resistance of shell=

=

Rate of heat flow = H

=

=

Let us consider an element (spherical shell) of thickness d and radius as shown in figure. Let us first find the equivalent thermal resistance between inner and outer sphere.

Resistance of shell=

=

Rate of heat flow = H

=

=

#### The figure shows a system of two concentric spheres of radii and and kept at temperatures and respectively. The radial rate of flow of heat in a substance between the two concentric spheres, is proportional to

physics-General

To measure the radial rate of heat flow, we have to go for integration technique as here the area of the surface through which heat will flow is not constant.

Let us consider an element (spherical shell) of thickness d and radius as shown in figure. Let us first find the equivalent thermal resistance between inner and outer sphere.

Resistance of shell=

=

Rate of heat flow = H

=

=

Let us consider an element (spherical shell) of thickness d and radius as shown in figure. Let us first find the equivalent thermal resistance between inner and outer sphere.

Resistance of shell=

=

Rate of heat flow = H

=

=

physics-

#### Two circular discs A and B with equal radii are blackened. They are heated to some temperature and are cooled under identical conditions. What inference do you draw from their cooling curves?

According to Newton’s law of cooling, rate of cooling is given by

Where c is specific heat of material.

or

rate of cooling varies inversely as specific heat. From the graph, for A rate of cooling is larger. Therefore, specific heat of A is smaller.

Where c is specific heat of material.

or

rate of cooling varies inversely as specific heat. From the graph, for A rate of cooling is larger. Therefore, specific heat of A is smaller.

#### Two circular discs A and B with equal radii are blackened. They are heated to some temperature and are cooled under identical conditions. What inference do you draw from their cooling curves?

physics-General

According to Newton’s law of cooling, rate of cooling is given by

Where c is specific heat of material.

or

rate of cooling varies inversely as specific heat. From the graph, for A rate of cooling is larger. Therefore, specific heat of A is smaller.

Where c is specific heat of material.

or

rate of cooling varies inversely as specific heat. From the graph, for A rate of cooling is larger. Therefore, specific heat of A is smaller.

physics-

#### Which of the curves in figure represents the relation between Celsius and Fahrenheit temperatures

Hence graph between and will be a straight line with positive slope and negative intercept

#### Which of the curves in figure represents the relation between Celsius and Fahrenheit temperatures

physics-General

Hence graph between and will be a straight line with positive slope and negative intercept

maths-

The area of circle centred at (1, 2) and passing through (4, 6) is

The area of circle centred at (1, 2) and passing through (4, 6) is

maths-General

physics-

#### Three rods of same dimensions are arranged as shown in figure. They have thermal conductivities and . The points and are maintained at different temperatures for the heat to flow at the same rate along and then which of the following options is correct

The given arrangement of rods can be redrawn as follows

It is given that

It is given that

#### Three rods of same dimensions are arranged as shown in figure. They have thermal conductivities and . The points and are maintained at different temperatures for the heat to flow at the same rate along and then which of the following options is correct

physics-General

The given arrangement of rods can be redrawn as follows

It is given that

It is given that

physics-

#### In the following diagram if then

#### In the following diagram if then

physics-General

physics-

#### The maximum kinetic energy (E_{k} ) of emitted photoelectrons against frequency v of incident radiation is plotted as shown in fig The slope of the graph is equal to

#### The maximum kinetic energy (E_{k} ) of emitted photoelectrons against frequency v of incident radiation is plotted as shown in fig The slope of the graph is equal to

physics-General

physics-

#### Which of the substance or has the highest specific heat? The temperature time graph is shown

Substances having more specific heat take longer time to get heated to a higher temperature and longer time to get cooled.

If we draw a line parallel to the time axis then it cuts the given graphs at three different points. Corresponding points on the times axis shows that

If we draw a line parallel to the time axis then it cuts the given graphs at three different points. Corresponding points on the times axis shows that

#### Which of the substance or has the highest specific heat? The temperature time graph is shown

physics-General

Substances having more specific heat take longer time to get heated to a higher temperature and longer time to get cooled.

If we draw a line parallel to the time axis then it cuts the given graphs at three different points. Corresponding points on the times axis shows that

If we draw a line parallel to the time axis then it cuts the given graphs at three different points. Corresponding points on the times axis shows that

maths-

#### The equation of the circumcircle of the triangle formed by the lines and y=0 is

#### The equation of the circumcircle of the triangle formed by the lines and y=0 is

maths-General