Surface area of a sphere

Q. The total surface area of a hemisphere having radius r is _____ .

1. $4\pi r^2$
2. $3\pi r^2$
3. $2\pi r^2$
4. $\frac{5}{2}\left(\pi r^2\right)$

Q.

A sphere and a hemisphere have same total surface area. Find the ratio of their radii i.e.$\frac{r_1}{r_2}$, where $r_1$ and $r_2$ are the radii of sphere and hemisphere respectively.

1. 1

2. $\frac{\sqrt{3}}{4}$

3. $\frac{3}{2}$

4. $\frac{\sqrt{3}}{2}$

Q.

Find the radius of a sphere whose surface area is $154{\mathrm{cm}}^2$. (Assume $\mathrm{\pi }=\frac{22}{7}$)

Q. If the radius of a circle is tripled, by how many times does It's circumference increase? How many times does it's area increase?

Q.

What is the surface area of a sphere?

1. 4$\pi$$r^2$

2. 2$\pi$$r^2$

3. $\frac{4}{3}$$\pi$$r^2$

4. $\frac{2}{3}$$\pi$$r^2$

Q.

Find the change in surface area of a sphere if its radius is increased 4 times.

1. Surface area increases 2 times

2. Surface area increases 16 times

3. Surface area decreases 2 times

4. Surface area decreases 16 times

Q.

A cricket ball of radius $r$ fits exactly into a cylindrical tin as shown in the figure below. What will be the ratio between the surface areas of the cricket ball and the tin?

1. 3:1

2. 2:3

3. 1:2

4. 3:5

Q.

What is the total surface area of a hemisphere?

1. 4$\pi$$r^2$

2. 2$\pi$$r^2$

3. $\frac{4}{3}$$\pi$$r^2$

4. 3$\pi$$r^2$

Q.

In a circus, a motorcyclist performs his stunts inside a hollow sphere. The thickness of the sphere is negligible. If the diameter of the hollow sphere is 14 m, then find the area available for the motorcyclist to perform his stunts.
$(use\pi =\frac{22}{7})$

1. 516 $m^2$

2. 616 $m^2$

3. 586 $m^2$

4. 486 $m^2$

Q.

If we take a circle and a hemisphere of the same radius, then the total surface area of the hemisphere is___ times the area of the circle.

Q.

If a hemisphere has radius __ cm, then total surface area of the hemisphere is 9.42 ${cm}^2$.

(Take $\pi$ = 3.14)

Q.

If we take a circle and a sphere of the same radius, then the surface area of the sphere is ___ times the area of the circle.

Q.

The radius of a hemisphere having total surface area of 1848 sq. cm is 7 cm.

1. True

2. False

Q.

The cost of painting outer curved surface of a hollow hemispherical iron bowl at the rate of ₹ 2 per cm square is ₹ 1256. If the thickness of the iron is 1 cm, find the cost of painting the inner curved surface of the bowl. (Take $\pi$ = 3.14)

1. ₹ 1076.32

2. ₹ 2034.72

3. ₹ 1017.36

4. ₹ 508.68

Q. The ratio of the volume and surface area of a sphere of unit radius:

1. $4:3$
2. $3:4$
3. $1:3$
4. $3:1$