Physics Questions and Answers

h = \( 6.6 \times 10^{-34}\)Js, 1eV =  \( 1.6 \times 10^{-19}\)J, \(E_1\) = - 8.6eV, \(E_2\) = - 3.5eV, f = ?

ΔE = hf 

f = \(\frac{ΔE}{h}\)

ΔE =  \(E_2\) -  \(E_1\) = - 3.5eV - (- 8.6eV) = 5.1eV

but 5.1eV = 5.1 X \( 1.6 \times 10^{-19}\) = \( 8.16 \times 10^{-19}\)J

f =  \(\frac{8.16 \times 10^{-19}}{ 6.6 \times 10^{-34}}\)

Therefore, f =  \( 1.24 \times 10^{15}\)Hz

The range of wavelengths for infrared waves is given as \(10^{-3}\) m  to \(10^{-6}\)m. This means that the wavelength of the radiation is longer than \(10^{-6} m\) but shorter than \{10^{-3} m\). Therefore, the only correct option is that the wavelength is longer than \(10^{-6} m\).

Maximum Range R = \(\frac{u^2sin2\theta}{g}\)

maximum height H = \(\frac{u^2sin^2\theta}{2g}\)

But R : H = 4

\(\frac{u^2sin2\theta}{g}\) :  \(\frac{u^2sin^2\theta}{2g}\) = 4

\(\frac{u^2sin2\theta}{g} \times\frac{2g}{u^2sin^2\theta}\) = 4

 \(\frac{2sin2\theta}{sin^2\theta}\) = 4 

since 2sinΘ = 2sinΘcosΘ

 \(\frac{2 \times 2sin\theta cos\theta}{sin^2\theta}\) = 4 

 \(\frac{4sin\theta cos\theta}{sin^2\theta}\) = 4 

\(\frac{sin\theta cos\theta}{sin^2\theta}\) = 1

\(\frac{cos\theta}{sin\theta}\) = 1

\(\frac{sin\theta}{cos\theta}\) = 1 

\(tan \theta\) = 1

\(\theta = tan^{-1}1\) = 45°

The work done in moving a charge across a potential difference is given by the formula W = QV, where W is the work done, Q is the charge and V is the potential difference. Substituting the given values, we get W = 10 C * 220 V = 2200 J. Hence, the work done is 2200 J.

f = 512Hz, V = 331m/s    λ  = ?

V = f λ 

λ  = \(\frac{v}{f} = \frac{331}{512}\)

λ  = 0.646m.

Distance between X and Y is the area of rectangular portion of the velocity-time graph.
XY = 40 × (8 - 4) = 40 × 4
∴ XY = 160 m

At resonance, the inductive reactance is equal to the capacitive reactance. This means that the voltage across the inductor is also equal to the voltage across the capacitor.

Therefore, the voltage across the capacitor is 40 V.

The type of mirror used by dentists to inspect the teeth of patients is a concave mirror.

Concave mirrors are curved inwards and produce a magnified image of the object placed within its focus and pole. This is why dentists use concave mirrors to examine teeth, as it allows them to see the teeth in more detail.

The correct statement about a ferromagnetic material is:

It has a high susceptibility.

Ferromagnetic materials are characterized by having a high susceptibility, which means they are strongly attracted to magnetic fields. When placed in a magnetic field, ferromagnetic materials become magnetized and can themselves exhibit strong magnetic properties, attracting other magnetic materials. Ferromagnetic materials, such as iron, nickel, and cobalt, are commonly used in the construction of permanent magnets and electromagnets due to their strong response to magnetic fields.

According to Newton's third law of motion, the force exerted on the bus by the towing vehicle is of the same magnitude as the force exerted on the towing vehicle by the bus (Statement II). The other statements are not necessarily true.