An electron (charge = 1.6 10^–19 coulomb) is moving in a circle of radius 5.1 10^–11m at a frequency of 6.8 × 10¹⁵ revolutions/sec. The equivalent current is approximately

Two wires A and B of same material and same mass have radius 2rand r. If resistance of wire A is , then resistance of B will be

In a neon discharge tube ions move to the right each second while electrons move to the left per second. Electron charge is . The current in the discharge tube

A platinum resistance thermometer has a resistance of at . When dipped in a liquid the resistance becomes . The temperature coefficient of resistance for platinum is . The temperature of the liquid is

For a metallic wire, the ratio V/i (V= the applied potential difference, i = current flowing) is

The centroid of the triangle ABC is (2, 3) and A = (4, 2), B = (4, 5) then the area of the
triangle ABC

For such questions, we should know the relation between centroid and vertices of a triangle. We should also know the formula of area using vertices of at triangle.

The points (6, 8), (–2, 2) and (–6, –1) form

25 men were employed to do a piece of work which they could finish in 20 days, but the men drop off by 5 at the end of every 10 days. In what time will the work be completed?

A can complete a piece of work in 15 days. B can complete it in 10 days. With the help of C, they can complete the work in 4 days. They all worked together and earned a total of Rs. 750. Find C’s share

L.C.M is the least common multiple. We should know the concepts of work and wages.

Three persons A, B and C finished a piece of work. A worked at it for 5 days, B for 7 days and C for 9 days. Their daily wages are in the ratio of 4 : 3 : 2 and the total earning amounted to Rs. 118. What was the daily wage of A?

A and B can do a piece of work in 40 days while B and C can do it in 60 days. If A is twice as good a workman as C, then C alone will do the work in

For such questions, we should know the concept of work and efficiency.

Meena, Neena and Raveena can knit a shawl in 6, 4 and 8 hours respectively. What portion of the shawl will they knit in 1 hour if they work together?

L.C.M is the smallest common multiple of the given numbers.

Tap A can fill a tank in 8 hours and tap B can empty the tank in 12 hours. How long would it take to fill the empty tank if both of them are opened together?

For such questions, we should see if the taps are filling or emptying the tank. We should also be careful about subtraction or addition of fractions. We should make the denominator equal or take L.C.M before subtracting or adding.

Latha, Chetan and Amar started a business. Latha invests Rs 5000 for 2 years, Chetan invests Rs.1000 for 15 months and Amar invests Rs 3000 for 10 months. If there is a profit of Rs. 1925, find out the share of Latha

The population of a town was 1,60,000 two years ago. If it has increased by 3% and 5% respectively in the last two years, find its present population

For such questions, we should be careful while finding the percentage increase in the population. We have to add the increased in number of population to the original population to get new population. We have to careful about order of increase in population.

The difference between C.I and S.I for 2 years at 10% per annum is Rs 50. Find the sum

For such questions, we should know the formulas for simple and compound interest.