1
AP EAPCET 2025 - 21st May Morning Shift
MCQ (Single Correct Answer)
+1
-0

In a plane electromagnetic wave, the magnetic field is given by $\mathbf{B}=3 \times 10^{-7} \sin \left(100 \pi x+10^{12} t\right) \mathrm{T}$, then the wavelength of the wave is

(In the equation $x$ is in metre and $t$ is in second)

A

0.02 m

B

0.2 m

C

0.4 m

D

0.04 m

2
AP EAPCET 2025 - 21st May Morning Shift
MCQ (Single Correct Answer)
+1
-0

If the linear momentum of a proton is changed by $p_0$ then the de-Broglie wavelength associated with the proton changes by $0.25 \%$. Then the initial linear momentum of the proton is

A

$100 p_0$

B

$\frac{p_0}{400}$

C

$400 p_0$

D

$\frac{p_0}{100}$

3
AP EAPCET 2025 - 21st May Morning Shift
MCQ (Single Correct Answer)
+1
-0

If an electron in the excited state falls to ground state, a photon of energy 5 eV is emitted, then the wavelength of the photon is nearly

A

748 nm

B

598 nm

C

398 nm

D

248 nm

4
AP EAPCET 2025 - 21st May Morning Shift
MCQ (Single Correct Answer)
+1
-0

An element $X$ of a half-life of $1.4 \times 10^9$ years decays to form another stable element $Y$. A sample is taken from a rock that contains both $X$ and $Y$ in the ratio $1: 7$. If at the time of formation of the rock $Y$ was not present in the sample, then the age of the rock in years is

A

$4.2 \times 10^9$

B

$1.4 \times 10^9$

C

$0.35 \times 10^9$

D

$2.8 \times 10^9$