A fuse is used in main electric supply as a safety device. Which one of the following statements about the fuse is correct?

Option (3) is correct. A fuse is a deliberately weak link placed in series with the circuit so that all circuit current passes through its fusible element; when excessive current flows the element heats and melts, breaking the circuit [1]. Fuses are therefore made from metals or alloys chosen for an appropriate (relatively low) melting point so they open reliably under overloads and short circuits; design aims for materials that melt easily and extinguish arcs when they do so. By contrast, a fuse is not connected in parallel and is not intended to have very high resistance during normal operation (it must conduct normally until melting) [2].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > 11.7.1 Practical Applications of Heating Effect of Electric Current > p. 190
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 11: Electricity > Activity 11.3 > p. 179