Construction of Concentric Circles

Q. If the radius of a circle is doubled, what happens to its circumference?

1. It get quadrupled
2. It gets doubled
3. It gets halved
4. It remains the same

Q. Two concentric circles form a ring. If the inner and outer circumferences of the ring are 20$\pi$ cm and 40$\pi$ cm respectively, then the width of the ring is ___.

1. 20 cm
2. 10 cm
3. 30 cm
4. 40 cm

Q.

In an archery board, the radius of the yellow circle is 5cm, and the radius of each of the next circles is 2 cm more than the previous ones. Find the diameter of the blue circle.

1. 22 cm

2. 18 cm

3. 49 cm

4. 9 cm

Q. Two concentric circles form a ring. If the inner and outer circumferences of the ring are 10$\pi$ cm and 30$\pi$ cm respectively, then the width of the ring is ___.

1. 10 cm
2. 40 cm
3. 20 cm
4. 30 cm

Q. What is common between two concentric circles?

1. Circular ring
2. Radius
3. Circumference
4. Centre

Q. Which of the drawings (a) to (d) shows:
$3\times \frac{2}{3}$

Q.

A circle has a circumference of 70 meters. Find its area. [2 MARKS]