List of top Geophysics Questions

Consider a steady-state heat conduction equation for the Earth’s crust where \( A \) is the heat source and \( k \) is the thermal conductivity. Given the boundary conditions: \( T = 0 \) at the surface and \( Q \) is the heat flux at the surface, Which one of the following options would be the temperature \( T \) at depth \( z \)?

In the schematic, line P shows a 1-D geothermal profile. If the heat flow at the base of the mantle increases, which line will reflect the new geothermal profile?


 

In levelling between two points A and B on the opposite banks of a river, the readings are taken by setting the instrument both at A and B, as shown in the table. If the RL of A is 150.000 m, the RL of B (in m) is ....... (rounded off to 3 decimal places). 

The maximum value of the function \( h(x) = -x^3 + 2x^2 \) in the interval \([-1, 1.5]\) is equal to ......... (rounded off to 1 decimal place).
Organic fraction of municipal solid waste (OFMSW) with bulk density of 315 kg/m$^3$ and water content of 30% is mixed with municipal sludge of bulk density 700 kg/m$^3$ and water content of 70%, such that the water content of the mixture is 40%. The amount (in kg) of sludge to be mixed per kg of OFMSW (rounded off to 2 decimal places) and the density of the mixture (in kg/m$^3$) (rounded off to the nearest integer) are calculated. Which of the following options is/are true:
If the horizontal distance between a staff point and the point of observation is \( d \), the error due to the curvature of the earth is proportional to
If the Fore Bearing of the lines AB and BC are 60° and 122°, respectively, then the interior angle \( \angle ABC \) (in degrees) is .......... (round off to the nearest integer).

Match the following in Column I with Column II.

The figure shows a propped cantilever with uniform flexural rigidity \( EI \) (in N.m\(^2\)) and subjected to a moment \( M \) (in N.m). Consider forces and displacements in the upward direction as positive.
Find the upward reaction at the propped support B (in N) when this support settles by \( \Delta \) (in metres).
 

A circular tube of thickness 10 mm and diameter 250 mm is welded to a flat plate using 5 mm fillet weld along the circumference. Assume Fe410 steel and shop welding.
As per IS 800:2007, the torque that can be resisted by the weld (in kN.m) is __________ (round off to one decimal place).
 

Free residual chlorine concentration in water was measured to be 2 mg/l (as Cl\(_2\)). The pH of water is 8.5. By using the chemical equation given below, the HOCl concentration (in \(\mu\)moles/l) in water is ___________ (round off to one decimal place).
\[ {HOCl} \rightleftharpoons {H}^+ + {OCl}^-, \quad pK = 7.50 \] Atomic weight: Cl = 35.5
 

Pick one or more CORRECT statement(s) from the choices given below, in the context of upstream and downstream cut-offs provided below the concrete apron of weirs/barrages constructed across alluvial rivers.
 

In the context of construction materials, which of the following statements is/are CORRECT?
 

The bacteria mainly responsible for crown corrosion in a sewer is ___________.
 

Given the following staff readings at two levels, determine the Reduced Level (RL) of B. 
staff readings at two levels
Given: - RL of A = 150 m - Find RL of B
Given the bearing N30°W, determine the corresponding Whole Circle Bearing (WCB). \
Whole Circle Bearing (WCB)
 Given: - Bearing = N30°W - Find WCB

Ultraviolet light of wavelength 350 nm and intensity \(1.00Wm^{−2 }\) falls on a potassium surface. The maximum kinetic energy of the photoelectron is

Higher-energy photons are scattered from electrons initially at rest. Assume the photons are backscattered ($\theta = 180^\circ$) and their energies are much higher than the electron's rest mass energy. The wavelength shift will be $\frac{h}{m_e c} = 2.43 \times 10^{-12} \, \text{m}$.
The value of the integral $$ \oint_C \left[ (x^3 + xy) \, dx + (x^2 - y^3) \, dy \right] $$ where $C$ is the square formed by the lines $x = \pm 1$, $y = \pm 1$, is: 
The shortest distance between the lines
$$ \frac{x-1}{2} = \frac{y-2}{3} = \frac{z-3}{4} $$ and
$$ \frac{x-2}{3} = \frac{y-4}{4} = \frac{z-5}{5} $$ is: 
In the matrix equation: \[ \begin{bmatrix} 3 & -1 \\ 2 & 5 \end{bmatrix} \begin{bmatrix} x \\ y \end{bmatrix} = \begin{bmatrix} 4 \\ -3 \end{bmatrix}, \] the values of \( x \) and \( y \) are:
If the radius of curvature of the Folium \( x^3 + y^3 - 3xy = 0 \) at the point \( (3/2, 3/2) \) is 5, then the value of \( b^2 + 2a + 1 \) is:
If A is a skew-symmetric matrix of odd order, then the determinant of A is:
Let P and Q be two matrices such that P Q = 0 and P is non-singular, then
(a) Q is also non-singular
(b) Q = 0
(c) Q is singular
(d) P = Q
Choose the correct answer from the options given below:
The value of curl (\(\text{grad } f\)), where \( f = x^2 - 4y^2 + 5z^2 \), is: