What standing wave ratio results from connecting a 50-ohm feed line to a 10-ohm resistive load?
Why SWR from a purely resistive mismatch is just the ratio of the larger value to the smaller: 50 ohms divided by 10 ohms gives 5, so the SWR is 5:1. The larger number always goes first because SWR is defined as the ratio of maximum to minimum voltage on the line and can never be less than 1. It does not matter whether the load is above or below the line impedance; a 250-ohm load on the same 50-ohm line would also read 5:1.
Watch out The choice written as 1:5 is the same arithmetic stated backwards, and SWR is never expressed that way; a reading below 1:1 is physically impossible.
Divide big by small, and the big number goes first. 50/10 = 5:1.