Để xác định khoảng cách đặt vật trước kính, ta sử dụng công thức:
$$\\ \\ \\ \\frac{1}{f} = \\frac{1}{d_o} + \\frac{1}{d_i}$$
Trong đó:
- f là tiêu cự của kính lúp (f = 15cm = 0.15m)
- do là khoảng cách từ vật đến kính lúp
- di là khoảng cách từ kính lúp đến mắt (di = 25cm = 0.25m)
Thay các giá trị vào công thức ta được:
$$\\ \\ \\ \\frac{1}{0.15} = \\frac{1}{d_o} + \\frac{1}{0.25}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\ \\frac{1}{0.15} - \\frac{1}{0.25} = \\frac{1}{d_o}$$
$$\\ \\ \\