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Four graphs are drawn with Celsius temperature C on the vertical axis and Fahrenheit temperature F on the horizontal axis, the origin (0,0) marked on each. Which of the following describes the graph that represents the relation between Celsius and Fahrenheit temperatures?

Asked in JEE Main 24th Jan 2nd Shift 2025 · Temperature scales

• (1) a line of positive slope cutting the F-axis to the right of the origin
• (2) a line of negative slope cutting the F-axis to the right of the origin
• (3) a line of positive slope passing through the origin
• (4) a line of negative slope passing through the origin

Step-by-step solution

Why the other options are wrong

• (2) comes from a negative slope would mean the Celsius reading falls as the Fahrenheit reading rises; the two scales measure the same hotness, so they must rise together.
• (3) comes from remembering only the ratio of degree sizes, 5/9, and dropping the 32 offset. A line through the origin would make 0 °F the ice point, but the ice point is 32 °F.
• (4) comes from carries both slips together — the offset dropped and the sense of the slope reversed.

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