IIT-JEE Exam

The largest wavelength in the ultraviolet region of the hydrogen spectrum is 122 nm. The smallest wavelength in the
infrared region of the hydrogen spectrum (to the nearest integer) is
(A) 802 nm (B) 823 nm
(C) 1882 nm (D) 1648 nm

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IIT-JEE Other Question

In an experiment to determine the focal length (f) of a concave mirror by the u–v method, a student places the object
pin A on the principal axis at a distance x from the pole P. The student looks at the pin and its inverted image from a
distance keeping his/her eye in line with PA. When the student shifts his/her eye towards left, the image appears to the
right of the object pin. Then,
(A) x < f (B) f < x < 2f
(C) x = 2f (D) x > 2f A resistance of 2 Ω is connected across one gap of a metre-bridge (the length of the wire is 100 cm) and an unknown
resistance, greater than 2Ω, is connected across the other gap. When these resistance are interchanged, the balance point
shifts by 20 cm. Neglecting any corrections, the unknown resistance is
(A) 3 Ω (B) 4 Ω
(C) 5 Ω (D) 6 Ω