In a lamp load, when more than one lamp are switched on, the total resistance of the load:

Explanation

In a lamp load where more than one lamp is switched on, the total resistance of the load decreases. This is because the lamps are typically connected in parallel to the power supply.When lamps are connected in parallel, each lamp has its own individual path for current to flow from the power supply. The voltage across each lamp is the same (equal to the supply voltage), and the current through each lamp depends on its individual resistance.The total resistance (R_total) of resistors connected in parallel is given by the formula:1/R_total = 1/R_1 + 1/R_2 + 1/R_3 + ... + 1/R_nwhere R_1, R_2, R_3, ..., R_n are the resistances of individual lamps.Since the resistance of each lamp is typically the same (assuming identical lamps), we can rewrite the formula as:1/R_total = n * (1/R_lamp)where n is the number of lamps and R_lamp is the resistance of an individual lamp.Now, as n (the number of lamps) increases, the term "n * (1/R_lamp)" becomes larger, making the value of 1/R_total smaller. Consequently, the total resistance (R_total) of the lamp load decreases as more lamps are switched on in parallel. This results in a higher total current flowing through the load, which leads to a brighter illumination overall.