Related Questions

When an open coiled helical compression spring is subjected to an axial compressive load, the maximum shear stress induced in the wire is (where D = Mean diameter of the spring coil, d = Diameter of the spring wire, K = Wahl's stress factor and W = Axial compressive load on the spring)
A $$\frac{{{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$
B $$\frac{{2{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$
C $$\frac{{4{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$
D $$\frac{{8{\text{WD}}}}{{\pi {{\text{d}}^3}}} \times {\text{K}}$$
When a closely-coiled helical spring of mean diameter (D) is subjected to an axial load (W), the deflection of the spring ($$\delta $$) is given by (where d = Diameter of spring wire, n = No. of turns of the spring and C = Modulus of rigidity for the spring material)
A $$\frac{{{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{C}}{{\text{d}}^4}}}$$
B $$\frac{{2{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{C}}{{\text{d}}^4}}}$$
C $$\frac{{4{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{C}}{{\text{d}}^4}}}$$
D $$\frac{{8{\text{W}}{{\text{D}}^3}{\text{n}}}}{{{\text{C}}{{\text{d}}^4}}}$$
একটি স্টেপ আপ ট্রান্সফরমারে, গৌণ কুণ্ডলীর পাকসংখ্যা মুখ্য কুন্ডলীর পাকসংখ্যার দ্বিগুণ। যদি মূখ্য কুন্ডলীকে কোন পরিবর্তী বিদ্যুৎ লাইনের সাথে সংযুক্ত করা হয়, তাহলে মুখ্য কুণ্ডলীর তুলনায় গৌণ কুণ্ডলীতে- (In a step up transformer, the number of turns in the secondary coil is twice to that of primary coil. If you apply an alternating current in the primary coil, then in the secondary coil compared to the primary coil-)
A তড়িৎ প্রবাহের মান দ্বিগুণ হবে (current will be doubled)
B তড়িৎ প্রবাহের মান অর্ধেক হবে (current will be halved)
C তড়িৎ বিভবের মান অর্ধেক হবে (voltage will be halved)
D তড়িৎ প্রবাহের মান সমান থাকবে (Current will remain the same)
Two closely-coiled helical springs 'A' and 'B' of the same material, same number of turns and made from same wire are subjected to an axial load W. The mean diameter of spring 'A' is double the mean diameter of spring 'B'. The ratio of deflections in spring 'B' to spring 'A' will be
A $$\frac{1}{8}$$
B $$\frac{1}{4}$$
C 2
D 4
Two closely coiled helical springs 'A' and 'B' are equal in all respects but the diameter of wire of spring 'A' is double that of spring 'B' The stiffness of spring 'B' will be __________ that of spring 'A'
A One-sixteenth
B One-eighth
C One-fourth
D One-half
In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will
A Increase
B Decrease
C Remain the same
D Initially increase and then decrease
A certain amount of current flows through a ring shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil?
A Decreases
B Increases
C Remains same
D First increases and then decreases depending on the depth of iron in¬sertion
A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will
A Increase
B Decrease
C Remain constant
D Be excessive
কোন এক পার্কের একটি দোলনায় ঝুলতে লোহার তার ব্যবহার করা হয়েছে। কয়েকজন ছেলে-মেয়ে দোলনায় যখন দোল খাচ্ছিল তখন এক বাচ্চার অভিভাবক লক্ষ্য করেন যে, ফুলন তার 1 m থেকে বৃদ্ধি পেয়ে 1.01 m হয়েছে এবং তারটির ব্যাস হ্রাস পেয়েছে। পয়সনের অনুপাত 0.2 হলে দোলনার তারের ব্যাস কতখানি হ্রাস পায় ? (The iron wires have been used in a park to swing. When some children are swinging, the length of the wire increases from I m to 1.01 m whereas the diameter of the wire decreases which is noticed by a guardian. If Poisson's ratio is 0.2, then how much the diameter of the wire decreases?) 
A 0.15%
B 0.18%
C 2.5%
D 0.25%
E 0.2%
A closely coiled helical spring is acted upon by an axial force. The maximum shear stress developed in the spring is $$\tau $$. The half of the length of the spring if cut off and the remaining spring is acted upon by the same axial force. The maximum shear stress in the spring in new condition will be
A $$\frac{\tau }{2}$$
B $$\tau $$
C $$2\tau $$
D $$4\tau $$

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