The power of a lens can be calculated using the formula: Power (P) = 1/f, where f is the focal length of the lens.

In this question, the given focal length is 50cm. To find the power, we substitute the value of f into the formula:

P = 1/50 = 0.02 dioptre

Option 1 states that the power is +2 dioptre. However, this is incorrect since the calculated power is 0.02 dioptre. Hence, the correct answer should be Alert - correct answer should be +0.02 dioptre.

Option 2 states that the power is +0.02 dioptre, which matches the calculated value and is the correct answer.

Option 3 states that the power is -0.5 dioptre. Since the given lens is convex, which means it converges light, the power cannot be negative. Therefore, this option is incorrect.

Option 4 states that the power is +0.5 dioptre. This value does not match the calculated power of 0.02 dioptre. Hence, this option is incorrect.

In summary, the correct answer is option 2, which states that the power of the convex