Which of the following statements is correct regarding the effect of impurities on the electrical conductivity of a solid?
The addition of impurities always decreases the electrical conductivity of a solid.
The addition of impurities always increases the electrical conductivity of a solid.
The effect of impurities on the electrical conductivity of a solid depends on the type of impurity and the type of solid.
The effect of impurities on the electrical conductivity of a solid is negligible and can be ignored.
The addition of impurities can either increase or decrease the electrical conductivity of a solid, depending on the type of impurity and the type of solid. In semiconductors, the addition of impurities such as boron or phosphorus can increase the electrical conductivity by creating more electrons or holes, respectively. However, in metals, the addition of impurities can decrease the electrical conductivity by creating defects that impede the flow of electrons. Hence, the effect of impurities on the electrical conductivity of a solid depends on the type of impurity and the type of solid.